Light Metals 2019 [1st ed.] 978-3-030-05863-0, 978-3-030-05864-7

Table of contents :
Front Matter ....Pages i-xxxiv
Front Matter ....Pages 1-1
Advances in Beneficiation of Low-Grade Bauxite (Lala Behari Sukla, Archana Pattanaik, Debabrata Pradhan)....Pages 3-10
Leaching Kinetics of Thermally-Activated, High Silica Bauxite (Hong Peng, Steven Peters, James Vaughan)....Pages 11-17
Rheological Improvements in Alumina Industry Clarification Circuits (Lawrence J. Andermann Jr., Adrian Mullins, Cameron Smyth, Clive Roscoe)....Pages 19-26
Improving the Reliability of Fluidized Bed Alumina Calciners by Suitable Refractory Lining Selection (Mariana A. L. Braulio, José R. Cunha, Austin J. Maxwell, Dean Whiteman, Victor C. Pandolfelli)....Pages 27-32
Valorization of Bauxite Residue: A Challenge that Leads to a Mentality Shift and Eventually Innovation (Yiannis Pontikes)....Pages 33-33
Synchronous Desulfurization and Desilication of Low-Grade and High-Sulfur Bauxite by a Flotation Process (Wencui Chai, Guihong Han, Yanfang Huang, Yijun Cao, Jiongtian Liu)....Pages 35-38
Preparing Alumina by an Electrolytic Method from Sulfuric Acid Leachate of Coal Fly Ash (Yuan Shi, Kai-xi Jiang, Ting-an Zhang, Guo-zhi Lv)....Pages 39-43
Front Matter ....Pages 45-45
Use of Two Filtration Stages for Bauxite Residue (Roberto Seno Jr., Rodrigo Aparecido Moreno, Heri Cristine Nakamura)....Pages 47-56
Environmental Friendly Transformation of the First and Oldest Alumina Refinery in the World (Laurent Bonel, Philippe Clerin, Laurent Guillaumont)....Pages 57-67
Accelerating Bauxite Residue Remediation with Microbial Biotechnology (T. C. Santini, K. Warren, M. Raudsepp, N. Carter, D. Hamley, C. McCosker et al.)....Pages 69-77
Simulation and Experiment Study on Carbonization Process of Calcified Slag with Different Ventilation Modes (Guanting Liu, Liu Yan, Xiaolong Li, Weihua Sun, Zimu Zhang, Ting’an Zhang)....Pages 79-85
An Ecological Approach to the Rehabilitation of Bauxite Residue (Elisa Di Carlo, Ronan Courtney)....Pages 87-92
Quantitative X-Ray Diffraction Study into Bauxite Residue Mineralogical Phases (John Vogrin, Harrison Hodge, Talitha Santini, Hong Peng, James Vaughan)....Pages 93-99
Technospheric Mining of Rare Earth Elements and Refractory Metals from Bauxite Residue (John Anawati, Gisele Azimi)....Pages 101-105
Migration of Iron, Aluminum and Alkali Metal Within Pre-reduced-Smelting Separation of Bauxite Residue (Jian Pan, Siwei Li, Deqing Zhu, Jiwei Xu, Jianlei Chou)....Pages 107-111
Front Matter ....Pages 113-113
Influence of Amine Additives on the Electrodeposition of Aluminum from AlCl3-Dimethyl Sulfone Electrolytes (S. A. Salman, Sangjae Kim, Kensuke Kuroda, Masazumi Okido)....Pages 115-119
Determination of the Intermetallic α-Phase Crystal Structure in Aluminum Alloys Solidified at Rapid Cooling Rates (Joseph Jankowski, Michael Kaufman, Amy Clarke, Krish Krishnamurthy, Paul Wilson)....Pages 121-127
Comparison of the Effects of B4C and SiC Reinforcement in Al-Si Matrix Alloys Produced via PM Method (Yavuz Kaplan, Engin Tan, Hakan Ada, Sinan Aksöz)....Pages 129-134
The Effects of Manganese (Mn) Addition and Laser Parameters on the Microstructure and Surface Properties of Laser Deposited Aluminium Based Coatings (O. S. Fatoba, S. A. Akinlabi, E. T. Akinlabi)....Pages 135-141
Understanding the Role of Cu and Clustering on Strain Hardening and Strain Rate Sensitivity of Al-Mg-Si-Cu Alloys (M. Langille, B. J. Diak, F. De Geuser, G. Guiglionda, S. Meddeb, H. Zhao et al.)....Pages 143-151
Production of the AA2196-TiB2 MMCs via PM Technology (Engin Tan, Yavuz Kaplan, Hakan Ada, Sinan Aksöz)....Pages 153-157
Retrogression-Reaging Behavior in Aluminum AA6013-T6 Sheet (Katherine E. Rader, Jon T. Carter, Louis G. Hector Jr., Eric M. Taleff)....Pages 159-164
Front Matter ....Pages 165-165
Advanced Characterization of the Cyclic Deformation and Damage Behavior of Al-Si-Mg Cast Alloys Using Hysteresis Analysis and Alternating Current Potential Drop Method (Jochen Tenkamp, Kevin Bleicher, Sven Klute, Karin Chrzan, Alexander Koch, Frank Walther)....Pages 167-175
3-D Microstructural Distribution and Mechanical Analysis of HPDC Hypereutectic Al-Si Alloys via X-Ray Tomography (J. Wang, S. M. Xiong)....Pages 177-185
Conditions for Retrogression Forming Aluminum AA7075-T6 Sheet (Katherine E. Rader, Matthew B. Schick, Jon T. Carter, Louis G. Hector Jr., Eric M. Taleff)....Pages 187-191
Influence of Silicon Phase Particles on the Thermal Conductivity of Al-Si Alloys (Wenping Weng, Hiromi Nagaumi, Xiaodong Sheng, Weizhong Fan, Xiaocun Chen, Xiaonan Wang)....Pages 193-198
Influence of Microstructure Development on Mechanical Properties of AlSi7MgCu Alloy (Davor Stanić, Zdenka Zovko Brodarac, Letian Li)....Pages 199-207
Fabrication and Characterization of Open Cell Aluminum Foams by Polymer Replication Method (Ceren Yagsi, Ozgul Keles)....Pages 209-215
Hot and Cold Rolling Behavior of AA5083 Aluminium Alloy (S. Das, Shiwani Meena, R. Sarvesha)....Pages 217-224
Front Matter ....Pages 1-1
Study on Tensile Behavior of High Vacuum Die-Cast AlSiMgMn Alloys (Haidong Zhao, Fei Liu, Chen Hu, Runsheng Yang, Fengzheng Sun)....Pages 227-234
The Effect of Manganese and Strontium on Iron Intermetallics in Recycled Al-7% Si Alloy (James Mathew, Prakash Srirangam)....Pages 235-240
The Effect of Thermo-Mechanical Processing on the Microstructure and Mechanical Properties of Modified SIMA Treated Al-7Si Alloy (Chandan Choudhary, K. L. Sahoo, D. Mandal)....Pages 241-249
Elevated-Temperature Low-Cycle Fatigue Behaviors of Al-Si 356 and 319 Foundry Alloys (S. Chen, K. Liu, X.-G. Chen)....Pages 251-257
High Conductivity Al-Si-Mg Foundry Alloys—Market, Production, Optimization and Development (Takeshi Saito, Petter Åsholt, Leonhard Heusler, Thomas Balkenhol, Kjetil R. Steen)....Pages 259-269
Influence of Die Soldering on Die Erosion and Soldering Layer Between Al Melts and Die in Al-Si-Fe Alloys (Jong Min Kim, Jeong IL Youn, Young Jig Kim)....Pages 271-276
Front Matter ....Pages 277-277
Coupled Fluid Flow and Heat Transfer Analysis of Ageing Heat Furnace (Mircea Popa, Ioan Sava, Marin Petre, Cătălin Ducu, Sorin Moga, Alexandra-Valerica Nicola et al.)....Pages 279-284
The Influence of the Distance Between the Plate and the Top Nozzles During the Soft Quenching Process of the 6061 Aluminium Alloy Plates (Gheorghe Dobra, Ioan Sava, Carmen Nicoleta Stănică, Marin Petre, Cătălin Ducu, Sorin Moga et al.)....Pages 285-293
Numerical Investigation on the Motion of Free-Floating Crystals During DC Casting of Aluminum Alloys (Qipeng Dong, Hiromi Nagaumi, Haitao Zhang, Tianpeng Qu, Jingkun Wang)....Pages 295-303
Numerical Modelling, Microstructural Evolution and Characterization of Laser Cladded Al-Sn-Si Coatings on Ti-6Al-4V Alloy (O. S. Fatoba, E. T. Akinlabi, S. A. Akinlabi, M. F. Erinosho)....Pages 305-313
The Influence of Quenching and Stretching Process Conditions of Aluminium Alloy Plates on Residual Stresses (Gheorghe Dobra, Ioan Sava, Cristian Theodor Stanescu, Cătălin Ducu, Sorin Moga, Decebal Dorin Bălășoiu et al.)....Pages 315-322
Characteristics of Surface Properties of Aluminum Flat Products Related with Different Annealing Temperature and Cleaning Properties (Emel Çalışkan, Sadık Kaan İpek, Ahmet Seisoğlu, Erdem Güler, Ali Ulus)....Pages 323-329
Comparative Electrochemical and Intergranular Corrosion-Resistance Testing of Wrought Aluminium Alloys (Varužan Kevorkijan, Lucija Skledar, Marko Degiampietro, Irena Lesjak, Teja Krumpak)....Pages 331-339
Nature of Grain Boundary Precipitates and Stress Corrosion Cracking Behavior in Al 7075 and 7079 Alloys (Ramasis Goswami)....Pages 341-348
Front Matter ....Pages 349-349
Effect of Homogenization on Al-Fe-Si Centerline Segregation of Twin-Roll Cast Aluminum Alloy AA 8011 (Sooraj Patel, Jyoti Mukhopadhyay)....Pages 351-355
Effect of Mg and Si Content in Aluminum Alloys on Friction Surfacing Processing Behavior (Jonas Ehrich, Arne Roos, Stefanie Hanke)....Pages 357-363
Mechanical Properties Evolution for 8xxx Foil Stock Materials by Alloy Optimization—Literature Review and Experimental Research (Erik Santora, Josef Berneder, Florian Simetsberger, Martin Doberer)....Pages 365-372
Effects of Zr Additions on Structure and Microhardness Evolution of Eutectic Al-6Ni Alloy (Chanun Suwanpreecha, Phromphong Pandee, Ussadawut Patakham, David C. Dunand, Chaowalit Limmaneevichitr)....Pages 373-377
Microstructure and Mechanical Properties of an Al-Zr-Er High Temperature Alloy Microalloyed with Tungsten (A. R. Farkoosh, David Dunand, David N. Seidman)....Pages 379-383
Effect of Nickel Foil Thickness on Microstructure and Microhardness of Steel/Aluminium Alloy Dissimilar Laser Welding Joints (Xiaonan Wang, Xiaming Chen, Wenping Weng, Hiromi Nagaumi, Jingzhe Zhou)....Pages 385-393
Residual Stress Characterization for Marine Gear Cases in As-Cast and T5 Heat Treated Conditions with Application of Neutron Diffraction (Joshua Stroh, Dimitry Sediako)....Pages 395-399
Microstructural and Dry Sliding Friction Studies of Aluminum Matrix Composites Reinforced PKS Ash Developed via Friction Stir Processing (R. S. Fono-Tamo, Esther Titilayo Akinlabi, Jen Tien-Chien)....Pages 401-406
Front Matter ....Pages 407-407
Comparison of Diversified Casting Methods on Mechanical and Microstructural Properties of 5754 Aluminum Alloy for Automotive Applications (Ali Ulaş Malcıoğlu, Çisem Doğan, Canan İnel)....Pages 409-415
The Effect of High Speed Direct Chill Casting on Microstructure and Mechanical Properties of Al-Mg-Si-Fe Alloy (Haitao Zhang, Dongtao Wang, Jianzhong Cui, Hiromi Nagaumi, Weizhong Fan)....Pages 417-422
Multi-Component High Pressure Die Casting (M-HPDC): Temperature Influence on the Bond Strength of Metal-Plastic-Hybrids Manufactured by M-HPDC (Patrick Messer, Arthur Bulinger, Uwe Vroomen, Andreas Bührig-Polaczek)....Pages 423-428
On Microstructures, Textures and Formability of AA6xxx Alloy Sheets from DC and CC Processing (Xiyu Wen, Randall Bowers, Shridas Ningileri)....Pages 429-434
Prototyping of a High Pressure Die Cast Al-Si Alloy Using Plaster Mold Casting to Replicate Corresponding Mechanical Properties (Toni Bogdanoff, Ehsan Ghassemali, Martin Riestra, Salem Seifeddine)....Pages 435-442
Reduction of Aluminium Ingot Cooling Time in DC Casting Process (Josée Colbert, André Larouche)....Pages 443-450
Impact of the Main Casting Process Parameters on Floating Crystals in Al Alloy DC-Cast Ingots (Mousa Javidani, Martin Fortier, Josée Colbert)....Pages 451-459
Front Matter ....Pages 461-461
Effect of Cu Addition on the Microstructure, Mechanical and Thermal Properties of a Piston Al-Si Alloy (Suwaree Chankitmunkong, Dmitry G. Eskin, Chaowalit Limmaneevichitr)....Pages 463-469
Effects of Sc and Zr Addition on Microstructure and Mechanical Properties of Al-3Cu-2Li Alloy (Yang Wang, Zheng Li, Ruizhi Wu)....Pages 471-480
Effects on Microstructure Evolution of Al-9Si-0.3Mg Alloy by Pyrometallurgically Produced Sr Master Alloy (İbrahim Göksel Hizli, Derya Dışpınar)....Pages 481-485
Microstructure Characterization and Properties of Cast Al-Si-Fe-Zn Alloys with High Thermal Conductivity (Chun Zou, Gu Zhong, Chu Qiu, Xinghui Gui)....Pages 487-492
Effects of Ag on the Microstructures and Mechanical Properties of Al-Mg Alloys (Haitao Zhang, Bo Zhang)....Pages 493-497
Front Matter ....Pages 499-499
The Preparation Methods and Application of Aluminum Foam (Xia Duan, Zhiwei Dai, Rong Xu, Ronghui Mao, Binna Song)....Pages 501-504
The Effects of Solidification Cooling Rates on the Mechanical Properties of an Aluminum Inline-6 Engine Block (Joshua Stroh, Austin Piche, Dimitry Sediako, Anthony Lombardi, Glenn Byczynski)....Pages 505-512
Improvements for the Recognition Rate of Surface Defects of Aluminum Sheets (Xiaoming Liu, Ke Xu, Dongdong Zhou)....Pages 513-518
Front Matter ....Pages 519-519
How to Limit the Heat Loss of Anode Stubs and Cathode Collector Bars in Order to Reduce Cell Energy Consumption (Marc Dupuis)....Pages 521-531
Transformation of a Potline from Conventional to a Full Flexible Production Unit (Roman Düssel, Albert Mulder, Louis Bugnion)....Pages 533-541
Modernisation of Sumitomo S170 Cells at Boyne Smelters Limited (Chris Corby, Hao Zhang, Madeleine Lewis, James Roberts)....Pages 543-552
Environmental Aspects of UC RUSAL’s Aluminum Smelters Sustainable Development (Viktor Mann, Viktor Buzunov, Vitaly Pingin, Aleksey Zherdev, Vyacheslav Grigoriev)....Pages 553-563
Copper Insert Collector Bar for Energy Reduction in 360 KA Smelter (Amit Jha, Amit Gupta, Vinay Tiwari, Shashidhar Ghatnatti, K. K. Pandey, S. K. Anand)....Pages 565-572
New Resource-Saving Technologies for Lining the Cathode with Un-shaped Lining Materials (Aleksandr V. Proshkin, Vitaly V. Pingin, Viktor Kh. Mann, Yuri M. Shtefanyuk, Anton S. Orlov)....Pages 573-581
Amperage Increase from 195 to 240 kA Through Pot Upgrading (Liu Ming, Yang Xiaodong, Liu Yafeng, Lu Yanfeng)....Pages 583-591
Front Matter ....Pages 593-593
A Transient Model of the Anodic Current Distribution in an Aluminum Electrolysis Cell (Sébastien Guérard, Patrice Côté)....Pages 595-603
A Numerical Study of Gas Production and Bubble Dynamics in a Hall-Héroult Reduction Cell (A. Cubeddu, V. Nandana, U. Janoske)....Pages 605-613
Thermoelectrical Design of Startup Fuses for Aluminum Reduction Cells (André Felipe Schneider, Donald P. Ziegler, Timothée Turcotte, Daniel Richard, Pascal Lavoie, Ryan Soncini et al.)....Pages 615-624
Modelling Study of Exhaust Rate Impact on Heat Loss from Aluminium Reduction Cells (Alexander Arkhipov, Ievgen Necheporenko, Alexander Mukhanov, Nadia Ahli, Khawla AlMarzooqi)....Pages 625-635
Finite Element Analysis of a Cylindrical Cathode Collector Bars Design (Olivier Lacroix, Richard Beeler, Hicham Chaouki, Louis Gosselin, Mario Fafard)....Pages 637-644
CFD Modeling of Alumina Diffusion and Distribution in Aluminum Smelting Cells (Xiaozhen Liu, Youjian Yang, Zhaowen Wang, Wenju Tao, Tuofu Li, Zhibin Zhao)....Pages 645-645
Study on Side Ledge Behavior Under Current Fluctuations Based on Coupled Thermo-electric Model (Hongliang Zhang, Qiyu Wang, Jie Li, Hui Guo, Jingkun Wang, Tianshuang Li)....Pages 647-655
Front Matter ....Pages 657-657
Alumina Feeding and Raft Formation: Raft Collection and Process Parameters (Sindre Engzelius Gylver, Nina Helene Omdahl, Ann Kristin Prytz, Astrid Johanne Meyer, Lorentz Petter Lossius, Kristian Etienne Einarsrud)....Pages 659-666
Evolution of Mechanical Resistance of Alumina Raft Exposed to the Bath in Hall-Héroult Cells (Sándor Poncsák, L. Rakotondramanana, László I. Kiss, T. Roger, S. Guérard, J.-F. Bilodeau)....Pages 667-673
Dynamic Modelling of Alumina Feeding in an Aluminium Electrolysis Cell (V. Bojarevics)....Pages 675-682
Development of a Mathematical Model to Follow Alumina Injection (Thomas Roger, László Kiss, Kirk Fraser, Sándor Poncsák, Sébastien Guérard, Jean-François Bilodeau)....Pages 683-688
The Micro- and Macrostructure of Alumina Rafts (Sindre Engzelius Gylver, Nina Helene Omdahl, Stein Rørvik, Ingrid Hansen, Andrea Nautnes, Sofie Nilssen Neverdal et al.)....Pages 689-696
Alumina Scale Composition and Growth Rate in Distribution Pipes (Ingrid Bokn Haugland, Ole Kjos, Arne Røyset, Per Erik Vullum, Thor Anders Aarhaug, Maths Halstensen)....Pages 697-706
Investigation on Scale Formation in Aluminium Industry by Means of a Cold-Finger (Daniel Perez Clos, Petter Nekså, Sverre Gullikstad Johnsen, Ragnhild E. Aune)....Pages 707-719
Front Matter ....Pages 721-721
Dry Barrier Powder Performance Update (Richard Jeltsch)....Pages 723-729
Investigation of Refractory Degradation in Hall-Héroult Cell (Bhavya Narang, Shanmukh Rajgire, Amit Gupta, Mahesh Sahoo, J. P. Nayak)....Pages 731-736
Thermogravimetric Analysis of Thermal Insulating Materials Exposed to Sodium Vapor (Raymond Luneng, Zhaohui Wang, Arne Petter Ratvik, Tor Grande)....Pages 737-744
Innovative Anode Coating Technology to Reduce Anode Carbon Consumption in Aluminum Electrolysis Cells (Ali Jassim, Najeeba Al Jabri, Saleh A. Rabbaa, Edouard G. Mofor, Jamil Jamal)....Pages 745-752
Theory and Practice of High Temperature Gas Baking Technology for Aluminium Electrolysis Cells (Li Yingwu, Wang Xudong, Wu Chengbo)....Pages 753-759
Research and Application of Direct Welding Technology on Super Large Section Conductor (Xudong Wang, Liying Wu, Qingguo Bai, Qianqian Wei)....Pages 761-769
Front Matter ....Pages 771-771
Transfer Processes in the Bath of High Amperage Aluminium Reduction Cell (Andrey Zavadyak, Peter Polyakov, Andrey Yasinskiy, Iliya Puzanov, Yuri Mikhalev, Sergey Shakhrai et al.)....Pages 773-777
Microstructure and Properties Analysis of Aluminium Smelter Crust (Shanghai Wei, Jingjing Liu, Chathuni Ranaweera, Tania Groutso, Mark Taylor)....Pages 779-785
Sideledge in Aluminium Cells: Further Considerations Concerning the Trench at the Metal-Bath Boundary (Asbjørn Solheim, Eirik Hjertenæs, Kati Tschöpe, Marian Kucharik, Nancy Jorunn Holt)....Pages 787-793
In Situ Evolution of the Frozen Layer Under Cold Anode (Donald Picard, Jayson Tessier, Dany Gauthier, Houshang Alamdari, Mario Fafard)....Pages 795-802
Aluminum Electrolysis with Multiple Vertical Non-consumable Electrodes in a Low Temperature Electrolyte (Guðmundur Gunnarsson, Guðbjörg Óskarsdóttir, Sindri Frostason, Jón Hjaltalín Magnússon)....Pages 803-810
Anode Overvoltages on the Industrial Carbon Blocks (Peter Polyakov, Andrey Yasinskiy, Andrey Polyakov, Andrey Zavadyak, Yuri Mikhalev, Iliya Puzanov)....Pages 811-816
Development of a Drag Probe for In Situ Velocity Measurement of Molten Aluminum in Electrolysis Cell (Samaneh Poursaman, Mounir Baiteche, Donald Picard, Donald Ziegler, Louis Gosselin, Mario Fafard)....Pages 817-825
Front Matter ....Pages 827-827
Understanding of Co-evolution of PFC Emissions in EGA Smelter with Opportunities and Challenges to Lower the Emissions (Ali Jassim, Sergey Akhmetov, Abdalla A. Alzarooni, Daniel Whitfield, Barry Welch)....Pages 829-836
Results from Fluoride Emission Reduction Projects in Alcoa Baie-Comeau (Yves Béliveau, Stephen J. Lindsay, Stephan Broek, Julie Dontigny, Carl Doré, Diego Oitaben et al.)....Pages 837-847
Validation of PFC Slope at Alcoa Canadian Smelters with Anode Effect Assessment and Future Implications to Add Low Voltage Emissions into Total PFC Emissions (Christine Dubois, Eliezer Batista, Luis Espinoza-Nava, Alexandre Dubreuil)....Pages 849-855
SPL as a Carbon Injection Source in an EAF: A Process Study (Vishnuvardhan Mambakkam, Robert Alicandri, Kinnor Chattopadhyay)....Pages 857-866
Migration Behavior of Fluorides in Spent Potlining During Vacuum Distillation Method (Nan Li, Lei Gao, Kinnor Chattopadhyay)....Pages 867-872
HF and SO2 Multipoint Monitoring on Large Gas Treatment Centers (GTCs) with Prewarning Abilities (Anders Sørhuus, Sivert Ose, Eivind Holmefjord)....Pages 873-878
DFT Study on COS Oxidation Reaction Mechanism (Jie Li, Tianshuang Li, Hongliang Zhang, Jingkun Wang, Kena Sun, Jin Xiao)....Pages 879-884
Front Matter ....Pages 885-885
Lengthy Power Interruptions and Pot Line Shutdowns (Alton Tabereaux, Stephen Lindsay)....Pages 887-895
High Amperage Operation at Alcoa Deschambault Booster Section (Patrice Doiron, Jayson Tessier, Donald Paul Ziegler)....Pages 897-903
Potroom Operations Contributing to Fugitive Roof Dust Emissions from Aluminium Smelters (David S. Wong, Margaret M. Hyland, Nursiani I. Tjahyono, David Cotton)....Pages 905-912
Advancement in Control Logic of Hindalco Low Amperage Pots (Shanmukh Rajgire, Amit Jha, Amit Gupta, Manoj Chulliparambil, Saroj Choudhary, Gaurav Verma et al.)....Pages 913-920
Front Matter ....Pages 921-921
Study on Preparation of Lithium Carbonate from Lithium-Rich Electrolyte (Wei Wang, Weijie Chen, Yuzhi Li, Kejing Wang)....Pages 923-927
The Application of the “Remote Data-Diagnosis Technology Service” (RDTS) for Aluminum Pot Line (Bo Hong, Qinghong Tian, Xiaobing Yi, Zhuojun Xie)....Pages 929-935
Front Matter ....Pages 937-937
No Personnel in Hazard Zones (Arild Håkonsen, Britt Elin Gihleengen, Vegard Innerdal)....Pages 939-943
The Industrial Application of Molten Metal Analysis (LIBS) (James Herbert, Jorge Fernandez, Robert De Saro, Joe Craparo)....Pages 945-952
Sheet Ingot Casting Improvements at TRIMET Essen (N. Towsey, G. Scheele, A. Luetzerath, E. Schoell)....Pages 953-959
Automated Billet Surface Inspection (Jean-Pierre Gagné, Rémi St-Pierre, Pascal Côté, Francis Caron)....Pages 961-966
Optical Emission Spectrometry (OES) Data-Driven Inspection of Inclusions in Wrought Aluminium Alloys (Varužan Kevorkijan, Tomaž Šustar, Irena Lesjak, Marko Degiampietro, Janez Langus)....Pages 967-972
Hydrogen Measurements Comparison in EN-AW 5083 Alloy (Luisa Marzoli, Federica Pascucci, Giuseppe Esposito, Silvia Koch, Giulio Timelli, Marcel Rosefort)....Pages 973-980
Front Matter ....Pages 981-981
Macrosegregation Modelling of Large Sheet Ingots Including Grain Motion, Solidification Shrinkage and Mushy Zone Deformation (Dag Mortensen, Øyvind Jensen, Gerd-Ulrich Grün, Andreas Buchholz)....Pages 983-990
Effect of Reversing Rotational Magnetic Field on Grain Size Refinement (Akihiro Minagawa, Koichi Takahashi, Shin-ichi Shimasaki)....Pages 991-997
A Reduction in Hot Cracking via Microstructural Modification in DC Cast Billets (Kathleen Bennett, Elli Tindall, Samuel R. Wagstaff, Kenzo Takahashi)....Pages 999-1005
Analysis of the Interplay Between Thermo-solutal Convection and Equiaxed Grain Motion in Relation to Macrosegregation Formation in AA5182 Sheet Ingots (Akash Pakanati, Knut Omdal Tveito, Mohammed M’Hamdi, Hervé Combeau, Miha Založnik)....Pages 1007-1013
Grain Refinement of Commercial EC Grade 1370 Aluminium Alloy for Electrical Applications (Massoud Hassanabadi, Shahid Akhtar, Lars Arnberg, Ragnhild E. Aune)....Pages 1015-1023
Effects of CO2 Cover Gas and Yttrium Additions on the Oxidation of AlMg Alloys (N. Smith, B. Gleeson, W. Saidi, A. Kvithyld, G. Tranell)....Pages 1025-1032
Behaviour of Aluminium Carbide in Al-Melts During Re-melting (Mertol Gökelma, Trygve Storm Aarnæs, Jürgen Maier, Bernd Friedrich, Gabriella Tranell)....Pages 1033-1039
Study of Controllable Inclusion Addition Methods in Al Melt (Jiawei Yang, Sarina Bao, Shahid Akthar, Yanjun Li)....Pages 1041-1048
Front Matter ....Pages 1049-1049
Furnace Atmosphere and Dissolved Hydrogen in Aluminium (Martin Syvertsen, Anne Kvithyld, Eilif Gundersen, Inge Johansen, Thorvald Abel Engh)....Pages 1051-1056
Miniature Vacuum Degassing System (Allen Chan, Ray Peterson)....Pages 1057-1062
Impact of the Filter Roughness on the Filtration Efficiency for Aluminum Melt Filtration (Claudia Voigt, Björn Dietrich, Mark Badowski, Margarita Gorshunova, Gotthard Wolf, Christos G. Aneziris)....Pages 1063-1069
Influence of the Wetting Behavior on the Aluminum Melt Filtration (Claudia Voigt, Lisa Ditscherlein, Eric Werzner, Tilo Zienert, Rafal Nowak, Urs Peuker et al.)....Pages 1071-1079
Aluminium Filtration by Bonded Particle Filters (Anne Kvithyld, Martin Syvertsen, Sarina Bao, Ulrik Aalborg Eriksen, Inge Johansen, Eilif Gundersen et al.)....Pages 1081-1088
Evaluation of Filtration Efficiency of Ceramic Foam Filters (CFF) Using a Hydraulic Water System (Massoud Hassanabadi, Petr Bilek, Shahid Akhtar, Ragnhild E. Aune)....Pages 1089-1095
Drain Free Filtration (DFF)—A New CFF Technology (Ulf Tundal, Idar Steen, Åge Strømsvåg, Terje Haugen, John Olav Fagerlie, Arild Håkonsen)....Pages 1097-1104
Laboratory Scale Study of Reverse Priming in Aluminium Filtration (Sarina Bao, Martin Syvertsen, Freddy Syvertsen, Britt Elin Gihleengen, Ulf Tundal, Tanja Pettersen)....Pages 1105-1111
Estimation of Aluminum Melt Filtration Efficiency Using Automated Image Acquisition and Processing (Hannes Zedel, Robert Fritzsch, Shahid Akhtar, Ragnhild E. Aune)....Pages 1113-1120
Front Matter ....Pages 1121-1121
Horizontal Single Belt Casting of Aluminum Sheet Alloys (Roderick Guthrie, Mihaiela Isac)....Pages 1123-1130
Cast Strip Surface Topography Study and Thermomechanical Processing of 1050 Alloy Produced by One Copper Shell Roll Caster (Dionysios Spathis, John Tsiros, Andreas Mavroudis)....Pages 1131-1135
Influence of Strip Thickness on As-Cast Material Properties of Twin-Roll Cast Aluminum Alloys (Vakur Uğur Akdoğan, Cemil Işıksaçan, Hatice Mollaoğlu Altuner, Onur Birbaşar, Mert Günyüz)....Pages 1137-1141
Softening Behavior of Direct Chill and Twin-Roll Cast AA 3105 Alloy (Mert Gülver, Onur Meydanoglu, Cemil Işıksaçan)....Pages 1143-1147
Front Matter ....Pages 1149-1149
Aluminum Holding Furnace Optimal Design Using the CFD Method and Factorial Approach (Mohamed I. Hassan Ali, Saeed Alshehhi, Cynthia Belt)....Pages 1151-1157
Artificial Intelligence to Optimize Melting Processes: An Approach Combining Data Acquisition and Modeling (Amin Rostamian, Stéphane Lesquereux, Marc Bertherat, Michel Rappaz)....Pages 1159-1164
Oxy-Fuel Technologies for Improved Efficiency in Aluminum Scrap Melting (Xavier Paubel, Frank Rheker, Sarah Juma, Stew Jepson, Dietmar Wieck, Bill Ollerton)....Pages 1165-1172
Electromagnetic Transfer and Circulation (ETAC) of Molten Aluminum Metal and Its Alloys (Robert Fritzsch, Jim Grayson)....Pages 1173-1178
Optimized Electromagnetic Stirring in Melting and Holding Furnaces (Joakim Andersson)....Pages 1179-1183
Front Matter ....Pages 1185-1185
Changing the Fineness of Calcined Petroleum Coke with Ball Race Mills (Jens-Peter Thiel, Jan Paepcke, Arne Hilck)....Pages 1187-1193
How to Appreciate the Coal Tar Pitch Impregnation on Coke Material? (Quentin Bernabé, Salima Belbachir, Christophe Bouché, Fabien Gaudière, Pierre-Louis Perrin, Laurent Vonna et al.)....Pages 1195-1203
A Study of Elastic and Crack Resistance Properties of the Anode Carbon Material (Dag Herman Andersen, Fabian Dedecker, Sacha Emam, Martin Walderhaug)....Pages 1205-1211
Challenges and Opportunities of Vacuum Compaction: Lessons Learnt from Retrofitting EGA-JA Paste Plant to Vacuum Compaction (Bienvenu Ndjom, Muhammad Shafiq Malik, Ahmed Al Marzouqi, Tapan Kumar Sahu, Saleh Ahmed Rabba, Najeeba Al Jabri)....Pages 1213-1220
Carbon Block Tracking Package Based on Vision Technology (Pierre Mahieu, Xavier Genin, Christophe Bouché, David Brismalein, Hervé Pédroli)....Pages 1221-1228
Physical and Chemical Characterization of Bio-Pitch as a Potential Binder for Anode (Ying Lu, Roozbeh Mollaabbasi, Donald Picard, Donald Ziegler, Houshang Alamdari)....Pages 1229-1235
Anode Quality Monitoring Using Advanced Data Analytics (Bilal Azennoud, Ameline Bernard, Vincent Bonnivard, Hervé Pedroli)....Pages 1237-1245
Reactivity of Coke in Relation to Sulfur Level and Microstructure (Gøril Jahrsengene, Stein Rørvik, Arne Petter Ratvik, Lorentz Petter Lossius, Richard G. Haverkamp, Ann Mari Svensson)....Pages 1247-1253
Front Matter ....Pages 1255-1255
Development of a New Baking Furnace Design Without Headwall to Increase Anode Production Capacity (Arnaud Bourgier, J. P. Schneider, Lise Lavigne, Yves Tremblay, Allan Graham, Meaghan Noonan)....Pages 1257-1267
Risk Assessment of Fire and Explosion Incident in Anode Baking Furnace and Operational Practices (Kalpataru Samal, Suryakanta Nayak, Pulak Patra)....Pages 1269-1274
The Optimization of Soaking Time to Reduce Fuel Consumption While Keeping Good Baked Anode Quality (S. S. Sijabat, Firman Ashad, Ivan Ermisyam, Ade Buandra, Daniel Jimmy P. Hutauruk, Ivan Eko Yudho)....Pages 1275-1280
Influence of Coke Calcining Level on Anode Real Density, LC and Other Properties Using a Constant Baking Cycle (Christopher Kuhnt, Les Edwards, Marvin Lubin, Kevin Harp)....Pages 1281-1289
In Situ Monitoring of Pit Gas Composition During Baking of Anodes for Aluminum Electrolysis (Trond Brandvik, Thor A. Aarhaug, Heiko Gaertner, Arne P. Ratvik, Tor Grande)....Pages 1291-1292
Measurement of Anode Anisotropy by Micro X-Ray Computed Tomography (Stein Rørvik, Lorentz Petter Lossius)....Pages 1293-1299
Experimental Study on Preparation of Prebake Anodes with High Sulfur Petroleum Coke Desulfurized at High Temperatures (Shoulei Gao, Jilai Xue, Guanghui Lang, Rui Liu, Chongai Bao, Zhiguo Wang et al.)....Pages 1301-1309
Electrochemical Behaviour of Carbon Anodes Produced with Different Mixing Temperatures and Baking Levels—A Laboratory Study (Camilla Sommerseth, Rebecca Jayne Thorne, Wojciech Gebarowski, Arne Petter Ratvik, Stein Rørvik, Hogne Linga et al.)....Pages 1311-1318
Front Matter ....Pages 1319-1319
Carbon Cathode Wear in Aluminium Electrolysis Cells (Samuel Senanu, Zhaohui Wang, Arne Petter Ratvik, Tor Grande)....Pages 1321-1322
Observation on the Creep and Cracking of Graphite Cathode in Laboratory Aluminum Electrolysis (Yunfei Lian, Jilai Xue, Cheng Zhang, Haipeng Li, Xuan Liu)....Pages 1323-1328
Electrolytic Properties and Element Migration Behavior of Fe-TiB2 Composite Cathode (Yudong Liang, Lijun Wang, Dengpeng Chai, Shengzhong Bao, Tingting Niu, Junwei Wang et al.)....Pages 1329-1334
Chemical Properties of Chromium Oxide in KF-NaF-AlF3 Based Low Temperature Electrolyte Melt (Shengzhong Bao, Yudong Liang, Dengpeng Chai, Zhirong Shi, Guanghui Hou, Yanhui Liu)....Pages 1335-1342
Front Matter ....Pages 1343-1343
Study Finer Fines in Anode Formulation (Case Study: Almahdi Hormozal Aluminium Smelter) (Alireza Fardani, Mohsen Ameri Siahooei, Borzu Baharvand)....Pages 1345-1348
Front Matter ....Pages 1349-1349
LIBS Based Sorting—A Solution for Automotive Scrap (Georg Rombach, Nils Bauerschlag)....Pages 1351-1357
A Method for Assessment of Recyclability of Aluminum from Incinerated Household Waste (Mertol Gökelma, Ingrid Meling, Ece Soylu, Anne Kvithyld, Gabriella Tranell)....Pages 1359-1365
The Vertical Floatation Decoater for Efficient, High Metal Yield Decoating and Delacquering of Aluminum Scrap (Robert De Saro, Sam Luke)....Pages 1367-1373
Positive Material Identification (PMI) Capabilities in the Metals Secondary Industry: An Analysis of XRF and LIBS Handheld Analyzers (Leslie Brooks, Gabrielle Gaustad)....Pages 1375-1380
Aluminum Alloys in Autobodies: Sources and Sinks (Ayomipo Arowosola, Gabrielle Gaustad, Leslie Brooks)....Pages 1381-1383
Manufacturing of Hydrogen on Demand Using Aluminum Can Scrap with Near Zero Waste (Jed Checketts, Neale R. Neelameggham)....Pages 1385-1387
Isothermal Hot Pressing of Skimmed Aluminium Dross: Influence of the Main Processing Parameters on In-House Molten-Metal Recovery (Varužan Kevorkijan)....Pages 1389-1392
Front Matter ....Pages 1393-1393
Scandium Solvent Extraction (Nigel J. Ricketts)....Pages 1395-1401
Refining Technology of Scandium Concentrate Obtained from Bauxite Residue (A. G. Suss, A. B. Kozyrev, S. N. Gorbachev, O. V. Petrakova, A. V. Panov)....Pages 1403-1406
Improved Technology of Scandium Recovery from Solutions of Bauxite Residue Carbonation Leaching (O. V. Petrakova, A. B. Kozyrev, A. G. Suss, S. N. Gorbachev, A. V. Panov)....Pages 1407-1413
Experimental Study of Pre-concentration from Silicate Containing Rare Earth Ore with Scandium by Magnetic Separation (Peng Yan, Guifang Zhang, Bo Li, Lei Gao, Zhe Shi, Hua Wang et al.)....Pages 1415-1420
Front Matter ....Pages 1421-1421
Grain Refinement of Al4CuTi Based Alloy with Zr, Sc, Er and TiB2 (Jiehua Li, Sajjad Amhad, Peter Schumacher)....Pages 1423-1429
Optimised Composition and Process Design to Develop Sc-Enhanced Wrought Al-Si Alloys (Jayshri Dumbre, Timothy Langan, Thomas Dorin, Nick Birbilis)....Pages 1431-1438
Developments in Aluminum-Scandium-Ceramic and Aluminum-Scandium-Cerium Alloys (David Weiss)....Pages 1439-1443
Developing an Optimized Homogenization Process for Sc and Zr Containing Al-Mg-Si Alloys (Steven Babaniaris, Mahendra Ramajayam, Lu Jiang, Timothy Langan, Thomas Dorin)....Pages 1445-1453
Effect of Scandium on Wire Arc Additive Manufacturing of 5 Series Aluminium Alloys (Andrew Sales, Nigel J. Ricketts)....Pages 1455-1461
Heat Treatments for Precipitation of Scandium-Containing Dispersoids in an Si-Containing Aluminum Alloys (Timothy Langan, Mahendra Ramjayam, Paul Sanders, Thomas Wood, Thomas Dorin)....Pages 1463-1467
Effect of Mg Content on Al3Sc-Dispersoid Formation in Cast Billets of Al-Mg-Sc Alloys (Carson Williams, Tom Wood, Paul Sanders, Timothy Langan)....Pages 1469-1471
Front Matter ....Pages 1473-1473
A Novel Flexible SSM and HPDC Equipment to Process Secondary Aluminium Alloys for Decarbonising Lightweight Parts in Automotive Sector (Fabrizio D’Errico, Guido Perricone, Mattia Alemani)....Pages 1475-1483
The Effects of Strontium Addition on the Microstructures and Mechanical Properties of Al-7Si Alloy Reinforced with In Situ Al3Ti Particulates (Siming Ma, Xiaoming Wang)....Pages 1485-1490
Mechanical and Microstructural Characterization of Ultrasonic Metal Welded Large Cross Section Aluminum Wire/Copper Terminal Joints (Andreas Gester, Guntram Wagner, Ingo Kesel, Friedhelm Guenter)....Pages 1491-1498
The Dependence of Local Strain Distribution on Quench Rate for Extruded Al-Mg-Si-Mn-Fe Alloys (Mojtaba Mansouri Arani, Nick Parson, Mei Li, Warren J. Poole)....Pages 1499-1501
The Effect of Through Thickness Texture Variation on the Anisotropic Mechanical Response of an Extruded Al-Mn-Fe-Si Alloy (Jingqi Chen, Warren J. Poole, Nick C. Parson)....Pages 1503-1505
Increasing the Strength and Electrical Conductivity of AA6101 Aluminum by Nanostructuring (Rilee C. Meagher, Mathew L. Hayne, Julie DuClos, Casey F. Davis, Terry C. Lowe, Tamás Ungár et al.)....Pages 1507-1513
Assessing the Impact of Texture and Its Gradients on the Forming Limits of an AA6xxx Sheet Alloy (Jishnu J. Bhattacharyya, Nathan Peterson, Fatih Sen, Richard Burrows, David Anderson, Vishwanath Hegadekatte et al.)....Pages 1515-1523
Front Matter ....Pages 1525-1525
Investigation on Acoustic Streaming During Ultrasonic Irradiation in Aluminum Melts (Takuya Yamamoto, Sergey Komarov)....Pages 1527-1531
Acoustic Cavitation Measurements and Modeling in Liquid Aluminum (Iakovos Tzanakis, Gerard Serge Bruno Lebon, Tungky Subroto, Dmitry Eskin, Koulis Pericleous)....Pages 1533-1538
Understanding the Highly Dynamic Phenomena in Ultrasonic Melt Processing by Ultrafast Synchrotron X-ray Imaging (Jiawei Mi, Dmitry Eskin, Thomas Connolley, Kamel Fezzaa)....Pages 1539-1544
The Influence of Ultrasound on the Microstructure Formation During Solidification of A356 Ingots Processed via a 2-Zone Induction Melting Furnace (Yang Xuan, Aqi Dong, Laurentiu Nastac)....Pages 1545-1550
Resonance from Contactless Ultrasound in Alloy Melts (C. E. H. Tonry, G. Djambazov, A. Dybalska, V. Bojarevics, W. D. Griffiths, K. A. Pericleous)....Pages 1551-1559
In Situ Tomographic Observation of Dendritic Growth in Mg/Al Matrix Composites (Enyu Guo, A. B. Phillion, Zongning Chen, Huijun Kang, Tongmin Wang, Peter D. Lee)....Pages 1561-1567
Anomalous Nucleation in Undercooled Melts Processed by Electromagnetic Levitation (Robert W. Hyers, Jie Zhao, Gwendolyn P. Bracker, Rainer Wunderlich, Hans Fecht)....Pages 1569-1572
Modeling of the Effect of Ultrasonic Frequency and Amplitude on Acoustic Streaming (Young Ki Lee, Jeong IL Youn, Young Jig Kim)....Pages 1573-1578
Mechanisms of Grain Formation During Ultrasonic Solidification of Commercial Purity Magnesium (B. Nagasivamuni, Gui Wang, David H. StJohn, Matthew S. Dargusch)....Pages 1579-1586
Front Matter ....Pages 1587-1587
Effect of Ultrasonication on the Solidification Microstructure in Al and Mg-Alloys (X. Zhang, H. R. Kotadia, J. Depner, M. Qian, A. Das)....Pages 1589-1595
Development and Application of Large-Sized Sonotrode Systems for Ultrasonic Treatment of Molten Aluminum Alloys (Sergey Komarov, Takuya Yamamoto)....Pages 1597-1604
Altering the Microstructure Morphology by Ultrasound Melt Processing During 6XXX Aluminium DC-Casting (G. Salloum-Abou-Jaoude, D. G. Eskin, G. S. B. Lebon, C. Barbatti, P. Jarry, M. Jarrett)....Pages 1605-1610
Effect of Acoustic Streaming on Degassing Level of A356 Al Alloy by Ultrasonic Melt Treatment (Jeong Il Youn, Young Ki Lee, Young Jig Kim, Ja Wook Koo)....Pages 1611-1615
Cellular Automation Finite Element Modeling of the Evolution of the As-Cast Microstructure of an Ultrasonically Treated Al-2Cu Alloy (Gui Wang, Paul Croaker, Matthew Dargusch, Damian McGuckin, David StJohn)....Pages 1617-1622
In Situ Detection of Non-metallic Inclusions in Aluminum Melt (1xxx)—Comparison Between a Newly Developed Ultrasonic Technique and LiMCA and PoDFA Method (Friederike Feikus, Florian Funken, Thomas Waschkies, Andreas Bührig-Polaczek)....Pages 1623-1629
Crystallization Behavior of Iron-Containing Intermetallic Compounds in Al-Si Alloy Under Ultrasonic Treatment (Yubo Zhang, Tongmin Wang, Tingju Li)....Pages 1631-1635
Microstructure and Mechanical Properties of Dispersion-Strengthened Aluminum-Magnesium Alloys Obtained Using Ultrasonic Treatment of Melt (Alexander Vorozhtsov, Anton Khrustalev, Ilya Zhukov, Alexander Kozulin, Evgeny Alifirenko)....Pages 1637-1640
Back Matter ....Pages 1641-1665

Citation preview

19 Edited by CORLEEN CHESONIS

The Minerals, Metals & Materials Series

Corleen Chesonis Editor

Light Metals 2019

123

Editor Corleen Chesonis Metal Quality Solutions, LLC Avonmore, PA, USA

ISSN 2367-1181 ISSN 2367-1696 (electronic) The Minerals, Metals & Materials Series ISBN 978-3-030-05863-0 ISBN 978-3-030-05864-7 (eBook) https://doi.org/10.1007/978-3-030-05864-7 Library of Congress Control Number: 2018964235 © The Minerals, Metals & Materials Society 2019 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Preface

It is my honor to present the Light Metals 2019 proceedings and to welcome you to the TMS 2019 Annual Meeting and Exhibition in San Antonio. I hope that being the second woman to edit this respected publication is an indication of increasing and ongoing inclusion and diversity in the light metals community. TMS has always been welcoming to me, both as a woman and as a chemical engineer rather than a metallurgist. The aluminum industry has continued to change in the past year with the announcement of Elysis, a joint venture to scale up and commercialize a revolutionary smelting technology that emits oxygen and eliminates greenhouse gases. If successful, this technology could help solve one of the major challenges of our industry and our world. In the meantime, a number of manufacturers have introduced certified low-carbon products and products made with 100% recycled metal. No matter what smelting technology is used in the future, recycling, reduced energy consumption, and lower environmental impact will continue to be important to our industry. These proceedings reflect an incredible effort by all the authors and their organizations in conducting their research and preparing the manuscripts that are published here. I would like to thank all of them for their work; their contributions continue to make Light Metals the pre-eminent annual publication for technical information on aluminum production processes. As in the past, this volume contains research and development papers on aluminum processes organized into the traditional Light Metals symposia: Alumina and Bauxite; Aluminum Alloys, Processing, and Characterization; Aluminum Reduction Technology; Cast Shop Technology; and Electrode Technology for Aluminum Production. It also includes two special symposia for 2019: Ultrasonic Processing of Liquid and Solidifying Alloys and Scandium Extraction and Use in Aluminum Alloys. We are honored to also have included papers on aluminum processing from two joint symposia: REWAS 2019: Cast Shop Recycling Technologies and the TMS-DGM Symposium on Lightweight Metals: A Joint US-European Symposium on Challenges in Light Weighting the Transportation Industry. This last symposium is the result of a Memorandum of Understanding between TMS and the German Materials Society (DGM). I would like to thank the subject chairs and symposium organizers for all of their hard work: Sébastien Fortin, Hiromi Nagaumi, Marc Dupuis, Pierre-Yves Menet, Lorentz Petter Lossius, Nigel Ricketts, John Grandfield, Dmitry Eskin, Mertol Gökelma, Eric Nyberg, Wim Sillekens, Norbert Hort, and Jürgen Hirsch. I also appreciate the guidance of the previous editors, Olivier Martin and Arne Ratvik. Finally, my sincere thanks to all the wonderful staff at TMS who guided us through the production of these proceedings. Corleen Chesonis

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Contents

Part I

Alumina & Bauxite: Bayer Process and Non-conventional Processing

Advances in Beneficiation of Low-Grade Bauxite . . . . . . . . . . . . . . . . . . . . . . . . Lala Behari Sukla, Archana Pattanaik and Debabrata Pradhan

3

Leaching Kinetics of Thermally-Activated, High Silica Bauxite . . . . . . . . . . . . . . Hong Peng, Steven Peters and James Vaughan

11

Rheological Improvements in Alumina Industry Clarification Circuits . . . . . . . . Lawrence J. Andermann Jr., Adrian Mullins, Cameron Smyth and Clive Roscoe

19

Improving the Reliability of Fluidized Bed Alumina Calciners by Suitable Refractory Lining Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mariana A. L. Braulio, José R. Cunha, Austin J. Maxwell, Dean Whiteman and Victor C. Pandolfelli

27

Valorization of Bauxite Residue: A Challenge that Leads to a Mentality Shift and Eventually Innovation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yiannis Pontikes

33

Synchronous Desulfurization and Desilication of Low-Grade and High-Sulfur Bauxite by a Flotation Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wencui Chai, Guihong Han, Yanfang Huang, Yijun Cao and Jiongtian Liu

35

Preparing Alumina by an Electrolytic Method from Sulfuric Acid Leachate of Coal Fly Ash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yuan Shi, Kai-xi Jiang, Ting-an Zhang and Guo-zhi Lv

39

Part II

Alumina & Bauxite: Bauxite Residue: Management and Valorization

Use of Two Filtration Stages for Bauxite Residue . . . . . . . . . . . . . . . . . . . . . . . . Roberto Seno Jr., Rodrigo Aparecido Moreno and Heri Cristine Nakamura Environmental Friendly Transformation of the First and Oldest Alumina Refinery in the World . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Laurent Bonel, Philippe Clerin and Laurent Guillaumont Accelerating Bauxite Residue Remediation with Microbial Biotechnology . . . . . . T. C. Santini, K. Warren, M. Raudsepp, N. Carter, D. Hamley, C. McCosker, S. Couperthwaite, G. Southam, G. W. Tyson and L. A. Warren Simulation and Experiment Study on Carbonization Process of Calcified Slag with Different Ventilation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Guanting Liu, Liu Yan, Xiaolong Li, Weihua Sun, Zimu Zhang and Ting’an Zhang An Ecological Approach to the Rehabilitation of Bauxite Residue . . . . . . . . . . . . Elisa Di Carlo and Ronan Courtney

47

57 69

79 87

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Contents

Quantitative X-Ray Diffraction Study into Bauxite Residue Mineralogical Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . John Vogrin, Harrison Hodge, Talitha Santini, Hong Peng and James Vaughan

93

Technospheric Mining of Rare Earth Elements and Refractory Metals from Bauxite Residue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . John Anawati and Gisele Azimi

101

Migration of Iron, Aluminum and Alkali Metal Within Pre-reduced-Smelting Separation of Bauxite Residue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jian Pan, Siwei Li, Deqing Zhu, Jiwei Xu and Jianlei Chou

107

Part III

Aluminum Alloys, Processing and Characterization: Aluminum Alloy Development

Influence of Amine Additives on the Electrodeposition of Aluminum from AlCl3-Dimethyl Sulfone Electrolytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. A. Salman, Sangjae Kim, Kensuke Kuroda and Masazumi Okido

115

Determination of the Intermetallic a-Phase Crystal Structure in Aluminum Alloys Solidified at Rapid Cooling Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joseph Jankowski, Michael Kaufman, Amy Clarke, Krish Krishnamurthy and Paul Wilson

121

Comparison of the Effects of B4C and SiC Reinforcement in Al-Si Matrix Alloys Produced via PM Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yavuz Kaplan, Engin Tan, Hakan Ada and Sinan Aksöz

129

The Effects of Manganese (Mn) Addition and Laser Parameters on the Microstructure and Surface Properties of Laser Deposited Aluminium Based Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O. S. Fatoba, S. A. Akinlabi and E. T. Akinlabi Understanding the Role of Cu and Clustering on Strain Hardening and Strain Rate Sensitivity of Al-Mg-Si-Cu Alloys . . . . . . . . . . . . . . . . . . . . . . . . M. Langille, B. J. Diak, F. De Geuser, G. Guiglionda, S. Meddeb, H. Zhao, B. Gault, D. Raabe and A. Deschamps

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143

Production of the AA2196-TiB2 MMCs via PM Technology . . . . . . . . . . . . . . . . Engin Tan, Yavuz Kaplan, Hakan Ada and Sinan Aksöz

153

Retrogression-Reaging Behavior in Aluminum AA6013-T6 Sheet . . . . . . . . . . . . Katherine E. Rader, Jon T. Carter, Louis G. Hector Jr. and Eric M. Taleff

159

Part IV

Aluminum Alloys, Processing and Characterization: Microstructures and Mechanical Properties of Aluminum Alloys

Advanced Characterization of the Cyclic Deformation and Damage Behavior of Al-Si-Mg Cast Alloys Using Hysteresis Analysis and Alternating Current Potential Drop Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jochen Tenkamp, Kevin Bleicher, Sven Klute, Karin Chrzan, Alexander Koch and Frank Walther

167

3-D Microstructural Distribution and Mechanical Analysis of HPDC Hypereutectic Al-Si Alloys via X-Ray Tomography . . . . . . . . . . . . . . . . . . . . . . . J. Wang and S. M. Xiong

177

Conditions for Retrogression Forming Aluminum AA7075-T6 Sheet . . . . . . . . . . Katherine E. Rader, Matthew B. Schick, Jon T. Carter, Louis G. Hector Jr. and Eric M. Taleff

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Influence of Silicon Phase Particles on the Thermal Conductivity of Al-Si Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wenping Weng, Hiromi Nagaumi, Xiaodong Sheng, Weizhong Fan, Xiaocun Chen and Xiaonan Wang

193

Influence of Microstructure Development on Mechanical Properties of AlSi7MgCu Alloy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Davor Stanić, Zdenka Zovko Brodarac and Letian Li

199

Fabrication and Characterization of Open Cell Aluminum Foams by Polymer Replication Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ceren Yagsi and Ozgul Keles

209

Hot and Cold Rolling Behavior of AA5083 Aluminium Alloy . . . . . . . . . . . . . . . S. Das, Shiwani Meena and R. Sarvesha Part V

217

Aluminum Alloys, Processing and Characterization: Behavior of Casting Alloys

Study on Tensile Behavior of High Vacuum Die-Cast AlSiMgMn Alloys . . . . . . . Haidong Zhao, Fei Liu, Chen Hu, Runsheng Yang and Fengzheng Sun

227

The Effect of Manganese and Strontium on Iron Intermetallics in Recycled Al-7% Si Alloy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . James Mathew and Prakash Srirangam

235

The Effect of Thermo-Mechanical Processing on the Microstructure and Mechanical Properties of Modified SIMA Treated Al-7Si Alloy . . . . . . . . . . Chandan Choudhary, K. L. Sahoo and D. Mandal

241

Elevated-Temperature Low-Cycle Fatigue Behaviors of Al-Si 356 and 319 Foundry Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. Chen, K. Liu and X.-G. Chen

251

High Conductivity Al-Si-Mg Foundry Alloys—Market, Production, Optimization and Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Takeshi Saito, Petter Åsholt, Leonhard Heusler, Thomas Balkenhol and Kjetil R. Steen Influence of Die Soldering on Die Erosion and Soldering Layer Between Al Melts and Die in Al-Si-Fe Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jong Min Kim, Jeong IL Youn and Young Jig Kim Part VI

259

271

Aluminum Alloys, Processing and Characterization: Simulations and Studies of Processing

Coupled Fluid Flow and Heat Transfer Analysis of Ageing Heat Furnace . . . . . Mircea Popa, Ioan Sava, Marin Petre, Cătălin Ducu, Sorin Moga, Alexandra-Valerica Nicola and Constantin-Nicușor Drăghici The Influence of the Distance Between the Plate and the Top Nozzles During the Soft Quenching Process of the 6061 Aluminium Alloy Plates . . . . . . . . . . . . . Gheorghe Dobra, Ioan Sava, Carmen Nicoleta Stănică, Marin Petre, Cătălin Ducu, Sorin Moga and Cristian Nicușor Florescu Numerical Investigation on the Motion of Free-Floating Crystals During DC Casting of Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Qipeng Dong, Hiromi Nagaumi, Haitao Zhang, Tianpeng Qu and Jingkun Wang

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Contents

Numerical Modelling, Microstructural Evolution and Characterization of Laser Cladded Al-Sn-Si Coatings on Ti-6Al-4V Alloy . . . . . . . . . . . . . . . . . . . O. S. Fatoba, E. T. Akinlabi, S. A. Akinlabi and M. F. Erinosho The Influence of Quenching and Stretching Process Conditions of Aluminium Alloy Plates on Residual Stresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gheorghe Dobra, Ioan Sava, Cristian Theodor Stanescu, Cătălin Ducu, Sorin Moga, Decebal Dorin Bălășoiu and Dan Ion Păun Characteristics of Surface Properties of Aluminum Flat Products Related with Different Annealing Temperature and Cleaning Properties . . . . . . . . . . . . . Emel Çalışkan, Sadık Kaan İpek, Ahmet Seisoğlu, Erdem Güler and Ali Ulus Comparative Electrochemical and Intergranular Corrosion-Resistance Testing of Wrought Aluminium Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Varužan Kevorkijan, Lucija Skledar, Marko Degiampietro, Irena Lesjak and Teja Krumpak Nature of Grain Boundary Precipitates and Stress Corrosion Cracking Behavior in Al 7075 and 7079 Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ramasis Goswami Part VII

305

315

323

331

341

Aluminum Alloys, Processing and Characterization: Characterizations and Applications of Aluminum Alloys

Effect of Homogenization on Al-Fe-Si Centerline Segregation of Twin-Roll Cast Aluminum Alloy AA 8011 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sooraj Patel and Jyoti Mukhopadhyay

351

Effect of Mg and Si Content in Aluminum Alloys on Friction Surfacing Processing Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jonas Ehrich, Arne Roos and Stefanie Hanke

357

Mechanical Properties Evolution for 8xxx Foil Stock Materials by Alloy Optimization—Literature Review and Experimental Research . . . . . . . . . . . . . . Erik Santora, Josef Berneder, Florian Simetsberger and Martin Doberer

365

Effects of Zr Additions on Structure and Microhardness Evolution of Eutectic Al-6Ni Alloy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chanun Suwanpreecha, Phromphong Pandee, Ussadawut Patakham, David C. Dunand and Chaowalit Limmaneevichitr

373

Microstructure and Mechanical Properties of an Al-Zr-Er High Temperature Alloy Microalloyed with Tungsten . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. R. Farkoosh, David Dunand and David N. Seidman

379

Effect of Nickel Foil Thickness on Microstructure and Microhardness of Steel/Aluminium Alloy Dissimilar Laser Welding Joints . . . . . . . . . . . . . . . . . Xiaonan Wang, Xiaming Chen, Wenping Weng, Hiromi Nagaumi and Jingzhe Zhou

385

Residual Stress Characterization for Marine Gear Cases in As-Cast and T5 Heat Treated Conditions with Application of Neutron Diffraction . . . . . . . . . . . . . . . . Joshua Stroh and Dimitry Sediako

395

Microstructural and Dry Sliding Friction Studies of Aluminum Matrix Composites Reinforced PKS Ash Developed via Friction Stir Processing . . . . . . . R. S. Fono-Tamo, Esther Titilayo Akinlabi and Jen Tien-Chien

401

Contents

xi

Part VIII

Aluminum Alloys, Processing and Characterization: Casting and Solidification

Comparison of Diversified Casting Methods on Mechanical and Microstructural Properties of 5754 Aluminum Alloy for Automotive Applications . . . . . . . . . . . . Ali Ulaş Malcıoğlu, Çisem Doğan and Canan İnel

409

The Effect of High Speed Direct Chill Casting on Microstructure and Mechanical Properties of Al-Mg-Si-Fe Alloy . . . . . . . . . . . . . . . . . . . . . . . . . Haitao Zhang, Dongtao Wang, Jianzhong Cui, Hiromi Nagaumi and Weizhong Fan

417

Multi-Component High Pressure Die Casting (M-HPDC): Temperature Influence on the Bond Strength of Metal-Plastic-Hybrids Manufactured by M-HPDC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Patrick Messer, Arthur Bulinger, Uwe Vroomen and Andreas Bührig-Polaczek On Microstructures, Textures and Formability of AA6xxx Alloy Sheets from DC and CC Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Xiyu Wen, Randall Bowers and Shridas Ningileri Prototyping of a High Pressure Die Cast Al-Si Alloy Using Plaster Mold Casting to Replicate Corresponding Mechanical Properties . . . . . . . . . . . . . . . . . . . . . . . Toni Bogdanoff, Ehsan Ghassemali, Martin Riestra and Salem Seifeddine Reduction of Aluminium Ingot Cooling Time in DC Casting Process . . . . . . . . . Josée Colbert and André Larouche Impact of the Main Casting Process Parameters on Floating Crystals in Al Alloy DC-Cast Ingots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mousa Javidani, Martin Fortier and Josée Colbert Part IX

423

429

435

443

451

Aluminum Alloys, Processing and Characterization: Poster Session I—Development of Aluminum Alloy Processing

Effect of Cu Addition on the Microstructure, Mechanical and Thermal Properties of a Piston Al-Si Alloy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Suwaree Chankitmunkong, Dmitry G. Eskin and Chaowalit Limmaneevichitr

463

Effects of Sc and Zr Addition on Microstructure and Mechanical Properties of Al-3Cu-2Li Alloy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yang Wang, Zheng Li and Ruizhi Wu

471

Effects on Microstructure Evolution of Al-9Si-0.3Mg Alloy by Pyrometallurgically Produced Sr Master Alloy . . . . . . . . . . . . . . . . . . . . . . . . . . İbrahim Göksel Hizli and Derya Dışpınar

481

Microstructure Characterization and Properties of Cast Al-Si-Fe-Zn Alloys with High Thermal Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chun Zou, Gu Zhong, Chu Qiu and Xinghui Gui

487

Effects of Ag on the Microstructures and Mechanical Properties of Al-Mg Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Haitao Zhang and Bo Zhang

493

Part X

Aluminum Alloys, Processing and Characterization: Poster Session II—Characterizations of Aluminum Alloys

The Preparation Methods and Application of Aluminum Foam . . . . . . . . . . . . . Xia Duan, Zhiwei Dai, Rong Xu, Ronghui Mao and Binna Song

501

xii

Contents

The Effects of Solidification Cooling Rates on the Mechanical Properties of an Aluminum Inline-6 Engine Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joshua Stroh, Austin Piche, Dimitry Sediako, Anthony Lombardi and Glenn Byczynski Improvements for the Recognition Rate of Surface Defects of Aluminum Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Xiaoming Liu, Ke Xu and Dongdong Zhou Part XI

505

513

Aluminum Reduction Technology: Cell Technology Development and Modeling

How to Limit the Heat Loss of Anode Stubs and Cathode Collector Bars in Order to Reduce Cell Energy Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . Marc Dupuis

521

Transformation of a Potline from Conventional to a Full Flexible Production Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Roman Düssel, Albert Mulder and Louis Bugnion

533

Modernisation of Sumitomo S170 Cells at Boyne Smelters Limited . . . . . . . . . . . Chris Corby, Hao Zhang, Madeleine Lewis and James Roberts Environmental Aspects of UC RUSAL’s Aluminum Smelters Sustainable Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Viktor Mann, Viktor Buzunov, Vitaly Pingin, Aleksey Zherdev and Vyacheslav Grigoriev Copper Insert Collector Bar for Energy Reduction in 360 KA Smelter . . . . . . . . Amit Jha, Amit Gupta, Vinay Tiwari, Shashidhar Ghatnatti, K. K. Pandey and S. K. Anand New Resource-Saving Technologies for Lining the Cathode with Un-shaped Lining Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aleksandr V. Proshkin, Vitaly V. Pingin, Viktor Kh. Mann, Yuri M. Shtefanyuk and Anton S. Orlov Amperage Increase from 195 to 240 kA Through Pot Upgrading . . . . . . . . . . . . Liu Ming, Yang Xiaodong, Liu Yafeng and Lu Yanfeng Part XII

543

553

565

573

583

Aluminum Reduction Technology: Cell Design and Modelling

A Transient Model of the Anodic Current Distribution in an Aluminum Electrolysis Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sébastien Guérard and Patrice Côté

595

A Numerical Study of Gas Production and Bubble Dynamics in a Hall-Héroult Reduction Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Cubeddu, V. Nandana and U. Janoske

605

Thermoelectrical Design of Startup Fuses for Aluminum Reduction Cells . . . . . . André Felipe Schneider, Donald P. Ziegler, Timothée Turcotte, Daniel Richard, Pascal Lavoie, Ryan Soncini and Jayson Tessier Modelling Study of Exhaust Rate Impact on Heat Loss from Aluminium Reduction Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alexander Arkhipov, Ievgen Necheporenko, Alexander Mukhanov, Nadia Ahli and Khawla AlMarzooqi Finite Element Analysis of a Cylindrical Cathode Collector Bars Design . . . . . . Olivier Lacroix, Richard Beeler, Hicham Chaouki, Louis Gosselin and Mario Fafard

615

625

637

Contents

xiii

CFD Modeling of Alumina Diffusion and Distribution in Aluminum Smelting Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Xiaozhen Liu, Youjian Yang, Zhaowen Wang, Wenju Tao, Tuofu Li and Zhibin Zhao

645

Study on Side Ledge Behavior Under Current Fluctuations Based on Coupled Thermo-electric Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hongliang Zhang, Qiyu Wang, Jie Li, Hui Guo, Jingkun Wang and Tianshuang Li

647

Part XIII

Aluminum Reduction Technology: Joint Session Alumina Feeding and Alumina Scale Formation

Alumina Feeding and Raft Formation: Raft Collection and Process Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sindre Engzelius Gylver, Nina Helene Omdahl, Ann Kristin Prytz, Astrid Johanne Meyer, Lorentz Petter Lossius and Kristian Etienne Einarsrud Evolution of Mechanical Resistance of Alumina Raft Exposed to the Bath in Hall-Héroult Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sándor Poncsák, L. Rakotondramanana, László I. Kiss, T. Roger, S. Guérard and J.-F. Bilodeau

659

667

Dynamic Modelling of Alumina Feeding in an Aluminium Electrolysis Cell . . . . V. Bojarevics

675

Development of a Mathematical Model to Follow Alumina Injection . . . . . . . . . . Thomas Roger, László Kiss, Kirk Fraser, Sándor Poncsák, Sébastien Guérard and Jean-François Bilodeau

683

The Micro- and Macrostructure of Alumina Rafts . . . . . . . . . . . . . . . . . . . . . . . Sindre Engzelius Gylver, Nina Helene Omdahl, Stein Rørvik, Ingrid Hansen, Andrea Nautnes, Sofie Nilssen Neverdal and Kristian Etienne Einarsrud

689

Alumina Scale Composition and Growth Rate in Distribution Pipes . . . . . . . . . . Ingrid Bokn Haugland, Ole Kjos, Arne Røyset, Per Erik Vullum, Thor Anders Aarhaug and Maths Halstensen

697

Investigation on Scale Formation in Aluminium Industry by Means of a Cold-Finger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Daniel Perez Clos, Petter Nekså, Sverre Gullikstad Johnsen and Ragnhild E. Aune Part XIV

707

Aluminum Reduction Technology: Joint Session with Electrode Technology

Dry Barrier Powder Performance Update . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Richard Jeltsch

723

Investigation of Refractory Degradation in Hall-Héroult Cell . . . . . . . . . . . . . . . Bhavya Narang, Shanmukh Rajgire, Amit Gupta, Mahesh Sahoo and J. P. Nayak

731

Thermogravimetric Analysis of Thermal Insulating Materials Exposed to Sodium Vapor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Raymond Luneng, Zhaohui Wang, Arne Petter Ratvik and Tor Grande

737

Innovative Anode Coating Technology to Reduce Anode Carbon Consumption in Aluminum Electrolysis Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ali Jassim, Najeeba Al Jabri, Saleh A. Rabbaa, Edouard G. Mofor and Jamil Jamal

745

Theory and Practice of High Temperature Gas Baking Technology for Aluminium Electrolysis Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Li Yingwu, Wang Xudong and Wu Chengbo

753

xiv

Contents

Research and Application of Direct Welding Technology on Super Large Section Conductor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Xudong Wang, Liying Wu, Qingguo Bai and Qianqian Wei Part XV

Aluminum Reduction Technology: Fundamentals in Cell Behavior, Inert Anodes and Other Research

Transfer Processes in the Bath of High Amperage Aluminium Reduction Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Andrey Zavadyak, Peter Polyakov, Andrey Yasinskiy, Iliya Puzanov, Yuri Mikhalev, Sergey Shakhrai, Nikita Sharypov, Olga Yushkova and Andrey Polyakov Microstructure and Properties Analysis of Aluminium Smelter Crust . . . . . . . . . Shanghai Wei, Jingjing Liu, Chathuni Ranaweera, Tania Groutso and Mark Taylor Sideledge in Aluminium Cells: Further Considerations Concerning the Trench at the Metal-Bath Boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asbjørn Solheim, Eirik Hjertenæs, Kati Tschöpe, Marian Kucharik and Nancy Jorunn Holt In Situ Evolution of the Frozen Layer Under Cold Anode . . . . . . . . . . . . . . . . . Donald Picard, Jayson Tessier, Dany Gauthier, Houshang Alamdari and Mario Fafard Aluminum Electrolysis with Multiple Vertical Non-consumable Electrodes in a Low Temperature Electrolyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Guðmundur Gunnarsson, Guðbjörg Óskarsdóttir, Sindri Frostason and Jón Hjaltalín Magnússon Anode Overvoltages on the Industrial Carbon Blocks . . . . . . . . . . . . . . . . . . . . . Peter Polyakov, Andrey Yasinskiy, Andrey Polyakov, Andrey Zavadyak, Yuri Mikhalev and Iliya Puzanov Development of a Drag Probe for In Situ Velocity Measurement of Molten Aluminum in Electrolysis Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Samaneh Poursaman, Mounir Baiteche, Donald Picard, Donald Ziegler, Louis Gosselin and Mario Fafard Part XVI

761

773

779

787

795

803

811

817

Aluminum Reduction Technology: Environmental Issues including PFC Emissions

Understanding of Co-evolution of PFC Emissions in EGA Smelter with Opportunities and Challenges to Lower the Emissions . . . . . . . . . . . . . . . . . . . . Ali Jassim, Sergey Akhmetov, Abdalla A. Alzarooni, Daniel Whitfield and Barry Welch Results from Fluoride Emission Reduction Projects in Alcoa Baie-Comeau . . . . . Yves Béliveau, Stephen J. Lindsay, Stephan Broek, Julie Dontigny, Carl Doré, Diego Oitaben and Sylvain Bouthillier Validation of PFC Slope at Alcoa Canadian Smelters with Anode Effect Assessment and Future Implications to Add Low Voltage Emissions into Total PFC Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Christine Dubois, Eliezer Batista, Luis Espinoza-Nava and Alexandre Dubreuil SPL as a Carbon Injection Source in an EAF: A Process Study . . . . . . . . . . . . . Vishnuvardhan Mambakkam, Robert Alicandri and Kinnor Chattopadhyay

829

837

849

857

Contents

xv

Migration Behavior of Fluorides in Spent Potlining During Vacuum Distillation Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nan Li, Lei Gao and Kinnor Chattopadhyay

867

HF and SO2 Multipoint Monitoring on Large Gas Treatment Centers (GTCs) with Prewarning Abilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anders Sørhuus, Sivert Ose and Eivind Holmefjord

873

DFT Study on COS Oxidation Reaction Mechanism . . . . . . . . . . . . . . . . . . . . . . Jie Li, Tianshuang Li, Hongliang Zhang, Jingkun Wang, Kena Sun and Jin Xiao Part XVII

879

Aluminum Reduction Technology: Cell Operations, Control and Improvements

Lengthy Power Interruptions and Pot Line Shutdowns . . . . . . . . . . . . . . . . . . . . Alton Tabereaux and Stephen Lindsay

887

High Amperage Operation at Alcoa Deschambault Booster Section . . . . . . . . . . Patrice Doiron, Jayson Tessier and Donald Paul Ziegler

897

Potroom Operations Contributing to Fugitive Roof Dust Emissions from Aluminium Smelters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . David S. Wong, Margaret M. Hyland, Nursiani I. Tjahyono and David Cotton Advancement in Control Logic of Hindalco Low Amperage Pots . . . . . . . . . . . . Shanmukh Rajgire, Amit Jha, Amit Gupta, Manoj Chulliparambil, Saroj Choudhary, Gaurav Verma, Vibhav Upadhyay and Senthil Nath Part XVIII

913

Aluminum Reduction Technology: Poster Session

Study on Preparation of Lithium Carbonate from Lithium-Rich Electrolyte . . . . Wei Wang, Weijie Chen, Yuzhi Li and Kejing Wang The Application of the “Remote Data-Diagnosis Technology Service” (RDTS) for Aluminum Pot Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bo Hong, Qinghong Tian, Xiaobing Yi and Zhuojun Xie Part XIX

905

923

929

Cast Shop Technology: EHS and Cast House Operation

No Personnel in Hazard Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arild Håkonsen, Britt Elin Gihleengen and Vegard Innerdal

939

The Industrial Application of Molten Metal Analysis (LIBS) . . . . . . . . . . . . . . . . James Herbert, Jorge Fernandez, Robert De Saro and Joe Craparo

945

Sheet Ingot Casting Improvements at TRIMET Essen . . . . . . . . . . . . . . . . . . . . N. Towsey, G. Scheele, A. Luetzerath and E. Schoell

953

Automated Billet Surface Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jean-Pierre Gagné, Rémi St-Pierre, Pascal Côté and Francis Caron

961

Optical Emission Spectrometry (OES) Data-Driven Inspection of Inclusions in Wrought Aluminium Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Varužan Kevorkijan, Tomaž Šustar, Irena Lesjak, Marko Degiampietro and Janez Langus Hydrogen Measurements Comparison in EN-AW 5083 Alloy . . . . . . . . . . . . . . . Luisa Marzoli, Federica Pascucci, Giuseppe Esposito, Silvia Koch, Giulio Timelli and Marcel Rosefort

967

973

xvi

Part XX

Contents

Cast Shop Technology: Casting and Cast House Products

Macrosegregation Modelling of Large Sheet Ingots Including Grain Motion, Solidification Shrinkage and Mushy Zone Deformation . . . . . . . . . . . . . . . . . . . . Dag Mortensen, Øyvind Jensen, Gerd-Ulrich Grün and Andreas Buchholz Effect of Reversing Rotational Magnetic Field on Grain Size Refinement . . . . . . Akihiro Minagawa, Koichi Takahashi and Shin-ichi Shimasaki A Reduction in Hot Cracking via Microstructural Modification in DC Cast Billets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kathleen Bennett, Elli Tindall, Samuel R. Wagstaff and Kenzo Takahashi

983

991

999

Analysis of the Interplay Between Thermo-solutal Convection and Equiaxed Grain Motion in Relation to Macrosegregation Formation in AA5182 Sheet Ingots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1007 Akash Pakanati, Knut Omdal Tveito, Mohammed M’Hamdi, Hervé Combeau and Miha Založnik Grain Refinement of Commercial EC Grade 1370 Aluminium Alloy for Electrical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1015 Massoud Hassanabadi, Shahid Akhtar, Lars Arnberg and Ragnhild E. Aune Effects of CO2 Cover Gas and Yttrium Additions on the Oxidation of AlMg Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1025 N. Smith, B. Gleeson, W. Saidi, A. Kvithyld and G. Tranell Behaviour of Aluminium Carbide in Al-Melts During Re-melting . . . . . . . . . . . . 1033 Mertol Gökelma, Trygve Storm Aarnæs, Jürgen Maier, Bernd Friedrich and Gabriella Tranell Study of Controllable Inclusion Addition Methods in Al Melt . . . . . . . . . . . . . . . 1041 Jiawei Yang, Sarina Bao, Shahid Akthar and Yanjun Li Part XXI

Cast Shop Technology: Melt Treatment

Furnace Atmosphere and Dissolved Hydrogen in Aluminium . . . . . . . . . . . . . . . 1051 Martin Syvertsen, Anne Kvithyld, Eilif Gundersen, Inge Johansen and Thorvald Abel Engh Miniature Vacuum Degassing System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1057 Allen Chan and Ray Peterson Impact of the Filter Roughness on the Filtration Efficiency for Aluminum Melt Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1063 Claudia Voigt, Björn Dietrich, Mark Badowski, Margarita Gorshunova, Gotthard Wolf and Christos G. Aneziris Influence of the Wetting Behavior on the Aluminum Melt Filtration . . . . . . . . . . 1071 Claudia Voigt, Lisa Ditscherlein, Eric Werzner, Tilo Zienert, Rafal Nowak, Urs Peuker, Natalia Sobczak and Christos G. Aneziris Aluminium Filtration by Bonded Particle Filters . . . . . . . . . . . . . . . . . . . . . . . . . 1081 Anne Kvithyld, Martin Syvertsen, Sarina Bao, Ulrik Aalborg Eriksen, Inge Johansen, Eilif Gundersen, Shahid Akhtar, Terje Haugen and Britt Elin Gihleengen Evaluation of Filtration Efficiency of Ceramic Foam Filters (CFF) Using a Hydraulic Water System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1089 Massoud Hassanabadi, Petr Bilek, Shahid Akhtar and Ragnhild E. Aune

Contents

xvii

Drain Free Filtration (DFF)—A New CFF Technology . . . . . . . . . . . . . . . . . . . . 1097 Ulf Tundal, Idar Steen, Åge Strømsvåg, Terje Haugen, John Olav Fagerlie and Arild Håkonsen Laboratory Scale Study of Reverse Priming in Aluminium Filtration . . . . . . . . . 1105 Sarina Bao, Martin Syvertsen, Freddy Syvertsen, Britt Elin Gihleengen, Ulf Tundal and Tanja Pettersen Estimation of Aluminum Melt Filtration Efficiency Using Automated Image Acquisition and Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1113 Hannes Zedel, Robert Fritzsch, Shahid Akhtar and Ragnhild E. Aune Part XXII

Cast Shop Technology: Continuous Casting

Horizontal Single Belt Casting of Aluminum Sheet Alloys . . . . . . . . . . . . . . . . . . 1123 Roderick Guthrie and Mihaiela Isac Cast Strip Surface Topography Study and Thermomechanical Processing of 1050 Alloy Produced by One Copper Shell Roll Caster . . . . . . . . . . . . . . . . . . 1131 Dionysios Spathis, John Tsiros and Andreas Mavroudis Influence of Strip Thickness on As-Cast Material Properties of Twin-Roll Cast Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1137 Vakur Uğur Akdoğan, Cemil Işıksaçan, Hatice Mollaoğlu Altuner, Onur Birbaşar and Mert Günyüz Softening Behavior of Direct Chill and Twin-Roll Cast AA 3105 Alloy . . . . . . . . 1143 Mert Gülver, Onur Meydanoglu and Cemil Işıksaçan Part XXIII

Cast Shop Technology: Energy Joint Session

Aluminum Holding Furnace Optimal Design Using the CFD Method and Factorial Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1151 Mohamed I. Hassan Ali, Saeed Alshehhi and Cynthia Belt Artificial Intelligence to Optimize Melting Processes: An Approach Combining Data Acquisition and Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1159 Amin Rostamian, Stéphane Lesquereux, Marc Bertherat and Michel Rappaz Oxy-Fuel Technologies for Improved Efficiency in Aluminum Scrap Melting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1165 Xavier Paubel, Frank Rheker, Sarah Juma, Stew Jepson, Dietmar Wieck and Bill Ollerton Electromagnetic Transfer and Circulation (ETAC) of Molten Aluminum Metal and Its Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1173 Robert Fritzsch and Jim Grayson Optimized Electromagnetic Stirring in Melting and Holding Furnaces . . . . . . . . 1179 Joakim Andersson Part XXIV

Electrode Technology for Aluminum Production: Electrodes—Raw Materials and Paste Plant

Changing the Fineness of Calcined Petroleum Coke with Ball Race Mills . . . . . . 1187 Jens-Peter Thiel, Jan Paepcke and Arne Hilck How to Appreciate the Coal Tar Pitch Impregnation on Coke Material? . . . . . . 1195 Quentin Bernabé, Salima Belbachir, Christophe Bouché, Fabien Gaudière, Pierre-Louis Perrin, Laurent Vonna and Roger Gadiou

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A Study of Elastic and Crack Resistance Properties of the Anode Carbon Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1205 Dag Herman Andersen, Fabian Dedecker, Sacha Emam and Martin Walderhaug Challenges and Opportunities of Vacuum Compaction: Lessons Learnt from Retrofitting EGA-JA Paste Plant to Vacuum Compaction . . . . . . . . . . . . . . . . . . 1213 Bienvenu Ndjom, Muhammad Shafiq Malik, Ahmed Al Marzouqi, Tapan Kumar Sahu, Saleh Ahmed Rabba and Najeeba Al Jabri Carbon Block Tracking Package Based on Vision Technology . . . . . . . . . . . . . . 1221 Pierre Mahieu, Xavier Genin, Christophe Bouché, David Brismalein and Hervé Pédroli Physical and Chemical Characterization of Bio-Pitch as a Potential Binder for Anode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1229 Ying Lu, Roozbeh Mollaabbasi, Donald Picard, Donald Ziegler and Houshang Alamdari Anode Quality Monitoring Using Advanced Data Analytics . . . . . . . . . . . . . . . . 1237 Bilal Azennoud, Ameline Bernard, Vincent Bonnivard and Hervé Pedroli Reactivity of Coke in Relation to Sulfur Level and Microstructure . . . . . . . . . . . 1247 Gøril Jahrsengene, Stein Rørvik, Arne Petter Ratvik, Lorentz Petter Lossius, Richard G. Haverkamp and Ann Mari Svensson Part XXV

Electrode Technology for Aluminum Production: Electrodes—Baking

Development of a New Baking Furnace Design Without Headwall to Increase Anode Production Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1257 Arnaud Bourgier, J. P. Schneider, Lise Lavigne, Yves Tremblay, Allan Graham and Meaghan Noonan Risk Assessment of Fire and Explosion Incident in Anode Baking Furnace and Operational Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1269 Kalpataru Samal, Suryakanta Nayak and Pulak Patra The Optimization of Soaking Time to Reduce Fuel Consumption While Keeping Good Baked Anode Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1275 S. S. Sijabat, Firman Ashad, Ivan Ermisyam, Ade Buandra, Daniel Jimmy P. Hutauruk and Ivan Eko Yudho Influence of Coke Calcining Level on Anode Real Density, LC and Other Properties Using a Constant Baking Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1281 Christopher Kuhnt, Les Edwards, Marvin Lubin and Kevin Harp In Situ Monitoring of Pit Gas Composition During Baking of Anodes for Aluminum Electrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1291 Trond Brandvik, Thor A. Aarhaug, Heiko Gaertner, Arne P. Ratvik and Tor Grande Measurement of Anode Anisotropy by Micro X-Ray Computed Tomography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1293 Stein Rørvik and Lorentz Petter Lossius Experimental Study on Preparation of Prebake Anodes with High Sulfur Petroleum Coke Desulfurized at High Temperatures . . . . . . . . . . . . . . . . . . . . . . 1301 Shoulei Gao, Jilai Xue, Guanghui Lang, Rui Liu, Chongai Bao, Zhiguo Wang and Fali Zhang

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Electrochemical Behaviour of Carbon Anodes Produced with Different Mixing Temperatures and Baking Levels—A Laboratory Study . . . . . . . . . . . . . . . . . . . 1311 Camilla Sommerseth, Rebecca Jayne Thorne, Wojciech Gebarowski, Arne Petter Ratvik, Stein Rørvik, Hogne Linga, Lorentz Petter Lossius and Ann Mari Svensson Part XXVI Electrode Technology for Aluminum Production: Cathodes and Electrode Technology Carbon Cathode Wear in Aluminium Electrolysis Cells . . . . . . . . . . . . . . . . . . . 1321 Samuel Senanu, Zhaohui Wang, Arne Petter Ratvik and Tor Grande Observation on the Creep and Cracking of Graphite Cathode in Laboratory Aluminum Electrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1323 Yunfei Lian, Jilai Xue, Cheng Zhang, Haipeng Li and Xuan Liu Electrolytic Properties and Element Migration Behavior of Fe-TiB2 Composite Cathode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1329 Yudong Liang, Lijun Wang, Dengpeng Chai, Shengzhong Bao, Tingting Niu, Junwei Wang and Ying Liu Chemical Properties of Chromium Oxide in KF-NaF-AlF3 Based Low Temperature Electrolyte Melt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1335 Shengzhong Bao, Yudong Liang, Dengpeng Chai, Zhirong Shi, Guanghui Hou and Yanhui Liu Part XXVII

Electrode Technology for Aluminum Production: Poster Session

Study Finer Fines in Anode Formulation (Case Study: Almahdi Hormozal Aluminium Smelter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1345 Alireza Fardani, Mohsen Ameri Siahooei and Borzu Baharvand Part XXVIII

REWAS 2019: Cast Shop Recycling Technologies: Cast Shop and Recycling Session

LIBS Based Sorting—A Solution for Automotive Scrap . . . . . . . . . . . . . . . . . . . 1351 Georg Rombach and Nils Bauerschlag A Method for Assessment of Recyclability of Aluminum from Incinerated Household Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1359 Mertol Gökelma, Ingrid Meling, Ece Soylu, Anne Kvithyld and Gabriella Tranell The Vertical Floatation Decoater for Efficient, High Metal Yield Decoating and Delacquering of Aluminum Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1367 Robert De Saro and Sam Luke Positive Material Identification (PMI) Capabilities in the Metals Secondary Industry: An Analysis of XRF and LIBS Handheld Analyzers . . . . . . . . . . . . . . 1375 Leslie Brooks and Gabrielle Gaustad Aluminum Alloys in Autobodies: Sources and Sinks . . . . . . . . . . . . . . . . . . . . . . 1381 Ayomipo Arowosola, Gabrielle Gaustad and Leslie Brooks Manufacturing of Hydrogen on Demand Using Aluminum Can Scrap with Near Zero Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1385 Jed Checketts and Neale R. Neelameggham

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Isothermal Hot Pressing of Skimmed Aluminium Dross: Influence of the Main Processing Parameters on In-House Molten-Metal Recovery . . . . . . . . . . . . . . . . 1389 Varužan Kevorkijan Part XXIX

Scandium Extraction and Use in Aluminum Alloys: Scandium Markets and Extraction

Scandium Solvent Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1395 Nigel J. Ricketts Refining Technology of Scandium Concentrate Obtained from Bauxite Residue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1403 A. G. Suss, A. B. Kozyrev, S. N. Gorbachev, O. V. Petrakova and A. V. Panov Improved Technology of Scandium Recovery from Solutions of Bauxite Residue Carbonation Leaching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1407 O. V. Petrakova, A. B. Kozyrev, A. G. Suss, S. N. Gorbachev and A. V. Panov Experimental Study of Pre-concentration from Silicate Containing Rare Earth Ore with Scandium by Magnetic Separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1415 Peng Yan, Guifang Zhang, Bo Li, Lei Gao, Zhe Shi, Hua Wang and Yindong Yang Part XXX

Scandium Extraction and Use in Aluminum Alloys: Aluminium Scandium Alloys

Grain Refinement of Al4CuTi Based Alloy with Zr, Sc, Er and TiB2 . . . . . . . . . 1423 Jiehua Li, Sajjad Amhad and Peter Schumacher Optimised Composition and Process Design to Develop Sc-Enhanced Wrought Al-Si Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1431 Jayshri Dumbre, Timothy Langan, Thomas Dorin and Nick Birbilis Developments in Aluminum-Scandium-Ceramic and Aluminum-Scandium-Cerium Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1439 David Weiss Developing an Optimized Homogenization Process for Sc and Zr Containing Al-Mg-Si Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1445 Steven Babaniaris, Mahendra Ramajayam, Lu Jiang, Timothy Langan and Thomas Dorin Effect of Scandium on Wire Arc Additive Manufacturing of 5 Series Aluminium Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1455 Andrew Sales and Nigel J. Ricketts Heat Treatments for Precipitation of Scandium-Containing Dispersoids in an Si-Containing Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1463 Timothy Langan, Mahendra Ramjayam, Paul Sanders, Thomas Wood and Thomas Dorin Effect of Mg Content on Al3Sc-Dispersoid Formation in Cast Billets of Al-Mg-Sc Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1469 Carson Williams, Tom Wood, Paul Sanders and Timothy Langan

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Part XXXI TMS-DGM Symposium on Lightweight Metals: A Joint US-European Symposium on Challenges in Light Weighting the Transportation Industry: Aluminum A Novel Flexible SSM and HPDC Equipment to Process Secondary Aluminium Alloys for Decarbonising Lightweight Parts in Automotive Sector . . . . . . . . . . . . 1475 Fabrizio D’Errico, Guido Perricone and Mattia Alemani The Effects of Strontium Addition on the Microstructures and Mechanical Properties of Al-7Si Alloy Reinforced with In Situ Al3Ti Particulates . . . . . . . . . 1485 Siming Ma and Xiaoming Wang Mechanical and Microstructural Characterization of Ultrasonic Metal Welded Large Cross Section Aluminum Wire/Copper Terminal Joints . . . . . . . . . . . . . . 1491 Andreas Gester, Guntram Wagner, Ingo Kesel and Friedhelm Guenter The Dependence of Local Strain Distribution on Quench Rate for Extruded Al-Mg-Si-Mn-Fe Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1499 Mojtaba Mansouri Arani, Nick Parson, Mei Li and Warren J. Poole The Effect of Through Thickness Texture Variation on the Anisotropic Mechanical Response of an Extruded Al-Mn-Fe-Si Alloy . . . . . . . . . . . . . . . . . . . 1503 Jingqi Chen, Warren J. Poole and Nick C. Parson Increasing the Strength and Electrical Conductivity of AA6101 Aluminum by Nanostructuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1507 Rilee C. Meagher, Mathew L. Hayne, Julie DuClos, Casey F. Davis, Terry C. Lowe, Tamás Ungár and Babak Arfaei Assessing the Impact of Texture and Its Gradients on the Forming Limits of an AA6xxx Sheet Alloy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1515 Jishnu J. Bhattacharyya, Nathan Peterson, Fatih Sen, Richard Burrows, David Anderson, Vishwanath Hegadekatte and Sean R. Agnew Part XXXII

Ultrasonic Processing of Liquid and Solidifying Alloys: Fundamental Studies of Ultrasonic Processing

Investigation on Acoustic Streaming During Ultrasonic Irradiation in Aluminum Melts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1527 Takuya Yamamoto and Sergey Komarov Acoustic Cavitation Measurements and Modeling in Liquid Aluminum . . . . . . . 1533 Iakovos Tzanakis, Gerard Serge Bruno Lebon, Tungky Subroto, Dmitry Eskin and Koulis Pericleous Understanding the Highly Dynamic Phenomena in Ultrasonic Melt Processing by Ultrafast Synchrotron X-ray Imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1539 Jiawei Mi, Dmitry Eskin, Thomas Connolley and Kamel Fezzaa The Influence of Ultrasound on the Microstructure Formation During Solidification of A356 Ingots Processed via a 2-Zone Induction Melting Furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1545 Yang Xuan, Aqi Dong and Laurentiu Nastac Resonance from Contactless Ultrasound in Alloy Melts . . . . . . . . . . . . . . . . . . . . 1551 C. E. H. Tonry, G. Djambazov, A. Dybalska, V. Bojarevics, W. D. Griffiths and K. A. Pericleous

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In Situ Tomographic Observation of Dendritic Growth in Mg/Al Matrix Composites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1561 Enyu Guo, A. B. Phillion, Zongning Chen, Huijun Kang, Tongmin Wang and Peter D. Lee Anomalous Nucleation in Undercooled Melts Processed by Electromagnetic Levitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1569 Robert W. Hyers, Jie Zhao, Gwendolyn P. Bracker, Rainer Wunderlich and Hans Fecht Modeling of the Effect of Ultrasonic Frequency and Amplitude on Acoustic Streaming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1573 Young Ki Lee, Jeong IL Youn and Young Jig Kim Mechanisms of Grain Formation During Ultrasonic Solidification of Commercial Purity Magnesium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1579 B. Nagasivamuni, Gui Wang, David H. StJohn and Matthew S. Dargusch Part XXXIII

Ultrasonic Processing of Liquid and Solidifying Alloys: Mechanisms and Applications of Ultrasonic Processing

Effect of Ultrasonication on the Solidification Microstructure in Al and Mg-Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1589 X. Zhang, H. R. Kotadia, J. Depner, M. Qian and A. Das Development and Application of Large-Sized Sonotrode Systems for Ultrasonic Treatment of Molten Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . 1597 Sergey Komarov and Takuya Yamamoto Altering the Microstructure Morphology by Ultrasound Melt Processing During 6XXX Aluminium DC-Casting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1605 G. Salloum-Abou-Jaoude, D. G. Eskin, G. S. B. Lebon, C. Barbatti, P. Jarry and M. Jarrett Effect of Acoustic Streaming on Degassing Level of A356 Al Alloy by Ultrasonic Melt Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1611 Jeong II Youn, Young Ki Lee, Young Jig Kim and Ja Wook Koo Cellular Automation Finite Element Modeling of the Evolution of the As-Cast Microstructure of an Ultrasonically Treated Al-2Cu Alloy . . . . . . . . . . . . . . . . . 1617 Gui Wang, Paul Croaker, Matthew Dargusch, Damian McGuckin and David StJohn In Situ Detection of Non-metallic Inclusions in Aluminum Melt (1xxx)—Comparison Between a Newly Developed Ultrasonic Technique and LiMCA and PoDFA Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1623 Friederike Feikus, Florian Funken, Thomas Waschkies and Andreas Bührig-Polaczek Crystallization Behavior of Iron-Containing Intermetallic Compounds in Al-Si Alloy Under Ultrasonic Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1631 Yubo Zhang, Tongmin Wang and Tingju Li Microstructure and Mechanical Properties of Dispersion-Strengthened Aluminum-Magnesium Alloys Obtained Using Ultrasonic Treatment of Melt . . . 1637 Alexander Vorozhtsov, Anton Khrustalev, Ilya Zhukov, Alexander Kozulin and Evgeny Alifirenko Author Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1641 Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1649

About the Editor

Corleen Chesonis is currently a consultant in aluminum metal treatment and molten metal quality with Metal Quality Solutions, LLC. She started her career with the Alcoa Technical Center in 1979, after receiving an M.S. in chemical engineering from Carnegie Mellon University. She worked as a research engineer on the Alcoa Smelting Process, the Hall-Héroult process, and organic matrix composite manufacturing processes. She completed her Ph.D. in chemical engineering in 1991 from the University of Pittsburgh as a part-time student while working at Alcoa. In 1992, she began working in Ingot Technology at the Alcoa Technical Center. She did research and plant support in the area of metal treatment and molten metal quality for more than 20 years. In 2016, she retired from Alcoa, but has remained active in the aluminum industry as a consultant. She has published 15 papers in the Cast Shop Technology field and has served as a session chair at multiple TMS meetings. She also served as subject chair for the Cast Shop Technology Symposium at the 2004 TMS Annual Meeting.

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Alumina and Bauxite Sébastien Fortin is R&D Principal Advisor for Bauxite and Alumina at Rio Tinto Aluminium Technology Solutions— ARDC. He holds a Ph.D. in inorganic chemistry from Université de Montréal. His career started at the Alcan Arvida Research and Development Centre in 2000, as a postdoctoral fellow conducting studies on heat exchangers scaling and cleaning. He spent the first 7 years of his career in R&D, driving projects on various aspects of the Bayer process, from bauxite characterization and Bayer process chemistry, to filtration and solid–liquid separation. He then spent nearly 4 years in operations, as process engineer at both Vaudreuil (Canada) and QAL (Australia) refineries, looking after redside and whiteside operation, where he made significant contributions in process improvements and equipment cleaning best practice. For the following 6 years, he was Bauxite and Alumina R&D Team Manager, successively at Gardanne (France) and ARDC, leading teams specializing in refinery process development, technical support, bauxite processability, and solid– liquid separation. Since the middle of 2017, he has been in charge of technical and strategic projects for Bauxite and Alumina R&D in the Atlantic region. His field of expertise is mainly bauxite and Bayer process chemistry. He is currently Rio Tinto, Atlantic, representative on the International Aluminium Institute’s Bauxite and Alumina Committee.

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Program Organizers

Aluminum Alloys, Processing, and Characterization Hiromi Nagaumi is a Professor and Director of Highperformance Metal Structural Materials Research Institute of Soochow University. He obtained his Ph.D. in metallurgical engineering at University of Electro-Communications (Japan) in 1997. He joined Nippon Light Metal Company as a senior research engineer in the casting research and development center from 1997 to 2007 and worked as vice-director from 2007 to 2009. Then, he worked for CHINALCO Suzhou Research Institute for Nonferrous Metals as vice-president and chief scientist from 2010 to 2017. In 2017, Hiromi joined Soochow University. He has long been engaged in the research of advanced melting and casting of aluminum alloys, and the design of new high-strength and high-toughness aluminum alloy materials for the lightweight of automobile. He first proposed the theory to predict the formation of porosities and hot-tearing within large-scale casting ingots. He successfully designed a new high-thermal conductivity aluminum alloys (180 W/m.K). He also managed to develop a new high-strength and toughness 6xxx alloys for automobile application (yield strength >380MPa, elongation >10%, fatigue strength >145MPa). He has served The Minerals, Metals & Materials Society (TMS) as session chair for Aluminum Alloys over several years.

Aluminum Reduction Technology Marc Dupuis has been a consultant specializing in the applications of mathematical modeling for the aluminum industry since 1994, the year he founded his own consulting company, GeniSim Inc. Before that, he graduated with a Ph.D. in chemical engineering from Laval University in Quebec City in 1984 and then worked for 10 years as a research engineer for Alcan International. His main research interests are the development of mathematical model of the Hall-Héroult cell dealing with the thermoelectric, thermomechanic, electromagnetic, and hydrodynamic aspect of the problem. He was also involved in the design of experimental high amperage cells and the retrofit of many existing cell technologies.

Program Organizers

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Cast Shop Technology Pierre-Yves Menet is Casting & Recycling R&D Group Manager at C-TEC, Constellium Technology Center in Voreppe, France. He graduated from Ecole Centrale Paris in 1989 with a master's degree in material science and engineering. In his career, he has held several positions from innovative research and development to industrialization of new processes and products as well as process optimization. Over this course, he has contributed to the continuous or semi-continuous casting process development of many products, slabs, billets, and strip, in most of the alloys of interest for the aluminum transformation industry including the recycling, remelting, and elaboration steps. During those projects, his main focus and motivation have been on developing process automation to ensure safety and quality and develop our understanding through process modeling. He also put together and structured the team within Constellium in charge of identifying and deploying good practices across Constellium casthouses. Today, his main interest is on making our profession more attractive to young talents and on developing the use of external (electromagnetic/ ultrasonic) fields in the casting and recycling process.

Cast Shop Technology: Energy Joint Session Pierre-Yves Menet (see above)

REWAS 2019: Cast Shop Recycling Technologies Mertol Gökelma is a Postdoctoral Researcher in the Department of Materials Science and Engineering at Norwegian University of Science and Technology (NTNU), Trondheim, Norway. He finished his B.Sc. at Dokuz Eylul University, Turkey in Metallurgical Engineering and Materials Science, and his M.Sc. and Ph.D. in Metallurgical Engineering at RWTH Aachen University, Germany. He worked as a research assistant for four years at the Institute of Process Technology and Metal Recycling (IME), RWTH. His research interests focus on process metallurgy of nonferrous metals and he has been involved in different R&D projects including recycling of magnesium black dross, recycling and refining of precious metals, powder synthesis of titanium alloys and metallothermic reduction of oxides. The main focus of his research is recycling and refining of aluminum as well as the behavior of nonmetallic inclusions in Al melts.

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Program Organizers

Electrode Technology for Aluminum Production Lorentz Petter Lossius is Principal Engineer with Hydro Aluminium. He was educated at the Norwegian University of Science and Technology with an M.Sc. in Chemistry, Instrumental Analysis in 1986, and completed his Dr.ing. at NTNU in 1991 with the thesis “Removing Impurities from Secondary Alumina”. In 1992–1993, he worked as a postdoc at the Université de Fribourg, Switzerland, studying Mg-battery electrochemistry, and from 1993 to 1996, he worked with Prof. Harald A. Øye as a research assistant/group leader at SINTEF/NTNU. In 1996, he joined Hydro Aluminium and is today Principal Engineer in the Anode Production section of the Primary Metal Technology research division. His main areas of work are research on anode raw materials and paste plant processing including pilot-scale studies, and development of laboratory methods and reference materials for X-ray characterization of in-plant process streams. Since 2002, he has been a Technical Expert in ISO Technical Committee 226 “Materials for the production of primary aluminium”, in 2006 as Convenor for Working Group 4 Smelter Grade Fluorides, and since 2011 Chair of ISO/TC226. He is Secretary of ASTM Sub-committee D02.05 “Properties of fuels, petroleum coke and carbon material”, and he is Committee Member of the biannual Norwegian X-ray Conference. He has authored and co-authored more than 40 papers, most based on original work performed at the Hydro plant and facilities in Årdal, Norway. He was an advisor in the selection of anode-related papers for the TMS Essential Readings in Light Metals collection (2013).

Scandium Extraction and Use in Aluminum Alloys Nigel Ricketts is Technical Director of Altrius Engineering Services, a consulting and technology firm in Brisbane, Australia. He has a Bachelor of Applied Science in metallurgy (South Australian Institute of Technology) and a Ph.D. in chemical engineering (Monash University). He has more than 30 years’ experience in extractive metallurgy and metal alloys research and development. He has conducted commissioning and plant operations, managed technology transfer, and developed and commercialised a number of technologies. He remains active in research with a current focus on copper and scandium extractive metallurgy and aluminum–scandium alloy development. He has five patents and has more than 30 conference and journal papers to his credit.

Program Organizers

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John Grandfield is Director of Grandfield Technology Pty Ltd, a consulting and technology firm, and Adjunct Professor at Swinburne University of Technology in the High Temperature Processing Group. He has a Bachelor of Applied Science in metallurgy (RMIT), an M.Sc. in mathematical modelling (Monash University), and a Ph.D. in materials science (University of Queensland). He has 30 years’ experience in light metals research and technology in smelting, continuous casting, and metal refining (Rio Tinto Alcan, CASTcrc, and CSIRO). He has conducted plant benchmarking audits and technology reviews, optimised existing technology, managed technology transfer, and developed and commercialised new casthouse technologies. He remains active in research with a current focus on ingot cavity control and inclusion removal. His work on direct-chill and ingot casting of aluminum and magnesium has been awarded both internationally and within Australia. He is regularly invited to give training courses, participate in in-house innovation workshops, and conduct R&D program reviews around the world. He has four patents, has published two book chapters and more than 50 conference and journal papers, and has co-authored a book on DC casting of light metals. He is a member of the TMS Aluminum Committee and was editor of Light Metals 2014.

Ultrasonic Processing of Liquid and Solidifying Alloys Dmitry G. Eskin received his Engineering and Ph.D. degrees from Moscow Institute of Steel and Alloys (Technical University, Russia) in 1985 and 1988, respectively. After that, he worked as a senior scientist in the Baikov Institute of Metallurgy (Russian Academy of Sciences) with a main research focus of alloy development, heat treatment, and metal processing of aluminum alloys. In 1999–2011, he was Senior Scientist and Fellow in Materials innovation institute and since 2008 also held a position of Associate Professor in Delft University of Technology (The Netherlands), where he conducted fundamental and applied research on solidification processing of metallic materials, with major contributions to direct-chill casting. In 2011, he joined Brunel University London (UK) as professor in Solidification Research. His current research concerns fundamentals and application of ultrasonic cavitation to melt processing. He is a well-known specialist in physical metallurgy and solidification processing of light alloys and author and co-author of more than 250 scientific papers, 7 monographs, and a number of patents. Among his books are Multicomponent Phase Diagrams: Applications for Commercial Aluminum Alloys (2005), Physical Metallurgy of Direct-Chill Casting of Aluminum Alloys (2008), Direct-Chill Casting of Light Alloys: Science and Technology (2013), and Solidification Processing of Metallic Alloys Under External Fields (2018). He has been a member of TMS since 2000, an organizer of a number of TMS symposia, and a regular speaker at TMS Annual Meetings.

xxx

Program Organizers

TMS-DGM Symposium on Lightweight Metals: A Joint US-European Symposium on Challenges in Light Weighting the Transportation Industry Eric Nyberg is the former Director of Programmes at Brunel University London, for the Brunel Centre for Advanced Solidification Technology (BCAST). He joined BCAST in 2016 to lead the development of research programs with international partners. Prior to this, he worked for 24 years at the Pacific Northwest National Laboratory (PNNL), most recently as chief engineer, materials research and development. The US Department of Energy (DOE) recognized Nyberg with the 2016 DOE Vehicle Technologies Office Special Recognition Award. He also holds three US patents and an R&D 100 Award and has authored or co-authored more than 50 technical publications. He earned both his bachelor’s and master’s degrees in materials science and engineering from Washington State University in Pullman, Washington. A TMS member since 1990, Nyberg was awarded the Light Metals Division (LMD) Distinguished Service Award in 2012. He has been engaged in LMD and TMS functional committees, including the Magnesium Committee Chair (Chair, Vice-Chair, and Secretary), the LMD Council (Vice-Chair), and the Program Committee (Magnesium Committee representative). He has also edited the Magnesium Technology Symposium proceedings and co-edited Essential Readings in Magnesium Technology (2014). Wim H. Sillekens is Materials Science Coordinator in the Directorate of Human and Robotic Exploration Programs of the European Space Agency (ESA), and in that capacity oversees ESA’s microgravity research program on materials science using such platforms as the International Space Station. He obtained his Ph.D. from Eindhoven University of Technology, The Netherlands, on a subject relating to metal-forming technology. Since then, he has been engaged in aluminum and magnesium research, among others on hydromechanical forming, recycling/refining, (hydrostatic) extrusion, forging, magnesium-based biodegradable implants, and most recently on light metal matrix nanocomposites and grain-refined materials. His professional career includes positions as a postdoc researcher at his alma mater and as a research scientist/project leader at the Netherlands Organization for Applied Scientific Research (TNO). International working experience includes a placement as a research fellow at MEL (now AIST) in Tsukuba, Japan. He has (co)-authored a variety of publications (about 150 entries to date). Other professional activities include an involvement in association activities (among others, as the lead organizer of TMS Magnesium Technology 2011), international conference committees, and as a peer reviewer of research papers and proposals. In 2017, he received the TMS Light Metals Division Distinguished Service Award.

Program Organizers

xxxi

Jürgen Hirsch is a Senior Consultant for Hydro Aluminium Rolled Products R&D Bonn; Professor at the Institute of Physical Metallurgy & Metal Physics (IMM), RWTH Aachen University; CTO of HoDforming GmbH Düsseldorf; Lecturer IUL at Technische Universität TU Dortmund; Guest Professor at Central South University, Changsha, China; and Remote Researcher at Samara National Research University, Russia. He is a member of the board of the German Society for Material Science (DGM), where he served as president in 2015-2016, and is head of FA “Aluminium”. He is also a member of the EUMAT EU platform steering committee and a member of the ICAA international committee, where he served as president from 2004 to 2016. He completed his Dr.-Ing. in material science and engineering at the IMM Institute of Physical Metallurgy & Metal Physics at the RWTH Aachen University in 1985. In 1988, he began work at Alcoa Technical Center (R&D) in Pittsburgh, USA, as a senior engineer. In 1991, he took a position as senior scientist at VAW Aluminium AG/Bonn (F&E), where he served as Head of Department for Rolling. This organization changed to Hydro Aluminium/Bonn (R&D) in 2002. In 2017, he became a consultant for “Aluminium—Metallurgy, Processing and Application”. He has authored more than 200 technical publications and articles and has edited several books on aluminum. Norbert Hort is the head of the Magnesium Processing Department at the Magnesium Innovation Centre (MagIC) within the Helmholtz-Zentrum Geesthacht, Geesthacht, Germany. Concurrently, he is Lecturer at Leuphana University, Lüneburg, Germany. He studied Materials Sciences at Clausthal University of Technology (CUT), Germany, where he has been involved in magnesium research since the early 1990s. In 1994, he obtained his university degree in engineering. He obtained his Ph.D. in materials sciences in 2002 from CUT. During 1994–1999, he worked as a researcher at the Institute of Materials Sciences (CUT), and he joined the MagIC in 2000. At MagIC, he is responsible for the development of new creep resistant alloys, biodegradable implant materials, and grain refinement and castability of magnesium alloys. This also covers in situ observations of solidification behavior using synchrotron diffraction and tomography. He is co-author of more than 190 peer reviewed journal articles and more than 220 contributions to conference proceedings. In recent years, he was involved in the organization of Magnesium Technology symposia at TMS Annual Meetings (2012–2014, 2018). Additionally, he was member of the organizing committees of Magnesium Alloys and their Applications (2009, 2012, 2015, 2018), LightMat (2013, 2017), Thermec (2013, 2016, 2018), Euromat 2017, IMA annual meetings (2013, 2014), and the conference “Light Metal Technologies 2011”. Since 2009, he has been Chairman of the technical committee “Magnesium” of the German Society of Materials (DGM).

Aluminum Committee 2018–2022

Chairperson Olivier Martin, Rio Tinto Alcan, Saint Jean, France

Vice Chairperson Corleen Chesonis, Metal Quality Solutions, LLC, Pennsylvania, USA

Past Chairperson Arne P. Ratvik, SINTEF, Trondheim, Norway

Director-at-Large Barry A. Sadler, Net Carbon Consulting Pty Ltd, Victoria, Australia

Secretary Stephan Broek, Hatch Ltd, Ontario, Canada

JOM Advisor Pascal Lavoie, Quebec, Canada

Light Metals Division Chair Alan A. Luo, The Ohio State University, Ohio, USA

Members-at-Large Through 2019 Marc Dupuis, GeniSim Inc, Quebec, Canada Bingliang Gao, Northeastern University, Shenyang, China

Members Through 2019 John V. Griffin, ACT LLC, New Jersey, USA Margaret M. Hyland, Victoria University of Wellington, Wellington, New Zealand Pascal Lavoie, Quebec, Canada Hans-Werner Schmidt, Outotec GmbH, Oberursel, Germany Alan David Tomsett, Pacific Aluminium, Queensland, Australia

Members Through 2020 Angelique N. Adams, Alcoa Inc, Tennessee, USA Stephen Broek, Hatch Ltd, Ontario, Canada Mohamed I. Hassan Ali, Masdar Institute of Science and Technology, Abu Dhabi, UAE Phil Black, Victoria, Australia Edward McRae Williams, Arconic, Pennsylvania, USA xxxiii

xxxiv

Members Through 2021 Arne P. Ratvik, SINTEF, Trondheim, Norway

Members Through 2022 Mark Badowski, Hydro Aluminium Rolled Products, Bonn, Germany Xian-An Liao, Elkem, Ontario, Canada Linus Perander, Outotec Gmbh & Co Kg, Stokke, Norway Xiyu Wen, University of Kentucky, Kentucky, USA

Aluminum Committee 2018–2022

Part I Alumina & Bauxite: Bayer Process and Non-conventional Processing

Advances in Beneficiation of Low-Grade Bauxite Lala Behari Sukla, Archana Pattanaik, and Debabrata Pradhan

Abstract

Bauxite is the major alumina (Al2O3) bearing ore used in the aluminum manufacturing industries. The bauxite containing less than 50% Al2O3 is called low-grade bauxite ore which is commonly used for the aluminabased abrasives and refractories productions. The alumina-silica and alumina-ferrite complexes are the foremost impurities present in the low-grade bauxite. They affect its commercial utilities due to development of poor binding property in the alumina grains, which creates mechano-physical problems. Therefore, they must be removed from the low-grade bauxite. Different conventional bauxite purification or beneficiation methods have been used for their removal; however, they have several limitations. Bio-beneficiation is a potential solution to the problems associated with conventional methods. In the bio-beneficiation process, the biological agents such as microorganisms and their metabolic products can mobilize or polarize different impurities present in the low-grade bauxite by means of the active redox environment created by them in the indigenous atmosphere. Many reports have suggested that Paenibacillus polymyxa efficiently removes calcium from the low-grade bauxite. Similarly, iron-oxidizing and silicate bacteria remove iron and solubilise silica, respectively, from the low-grade bauxite. However, pilot scale operation of the bauxite bio-beneficiation process has not been reported. Research

L. B. Sukla (&)
A. Pattanaik
D. Pradhan (&) Biofuels and Bioprocessing Research Center, Institute of Technical Education and Research, Siksha ‘O’ Anusandhan (Deemed to be University), Jagamara, Khandagiri, Bhubaneswar, 751030, Odisha, India e-mail: [email protected] D. Pradhan e-mail: [email protected] A. Pattanaik e-mail: [email protected]

related to biotechnology should be undertaken in the future to develop a comprehensive and efficient process for the bio-beneficiation of low-grade bauxite ore.




Keywords

Bauxite Beneficiation Desilication




Bacteria




Redox reaction




Introduction Aluminum industries use bauxite as the major raw material. Bauxite containing less than 50% Al2O3 is called low-grade bauxite ore, which is generally used for the production of aluminum appliances such as abrasives, ceramics, and refractories. The presence of impurities, including silica, iron oxides, and calcium contribute to the bauxite being classified as a low-grade ore. Secondly, calcium present in the low-grade bauxite should be less than 0.5% for the production of abrasives [1]. Similarly, hematite (Fe2O3) content should be as low as 1% for refractory applications. The impurities in the bauxite affect its utilities and lead to an increase in production cost. Additionally, higher concentrations of impurities in the bauxite can hinder the efficiency of the Bayer process, which is the major alumina refining process used throughout the aluminium industry. Therefore, there is a need for the beneficiation of bauxite to selectively remove impurities and thereby improving its economic value. Several physicochemical methods are being employed in removal of impurity from bauxite such as gravity separation, magnetic separation, froth flotation etc. However these conventional methods have several disadvantages, including high cost, increased energy consumption, reduced flexibility and environmental challenges [2]. Many attempts have been made to minimize the production cost and energy consumption by using advanced techniques and machinery modification. An increasing effort is being devoted to search

© The Minerals, Metals & Materials Society 2019 C. Chesonis (ed.), Light Metals 2019, The Minerals, Metals & Materials Series, https://doi.org/10.1007/978-3-030-05864-7_1

3

4 Table 1 Data collected from Mineral Commodity Summaries, 2012 gives view of world bauxite reserves by country

L. B. Sukla et al. Country

Reserves (in ‘000 tonnes)

Guinea

7,400,000

Australia

6,200,000

Brazil

3,600,000

Vietnam

2,100,000

Jamaica

2,000,000

India

900,000

Guyana

850,000

China

830,000

Greece

600,000

Suriname

580,000

Venezuela

320,000

Russia

200,000

Kazakhstan

160,000

USA

for alternative methods for beneficiation of bauxite. A better and more convincing solution to the above problem take a biotechnological approach [3–5]. These phenomenon are ecofriendly, cost effective, and do not require significant technical expertise. Biological methods of beneficiation provide a number of advantages over conventional approaches. India has the 6th largest bauxite reserve in the world (Table 1). Utilization of this bauxite would contribute significantly to the Indian economy. Therefore, development of these advanced beneficiation technologies should be a priority for the government and different research institutes in order to assist with accelerating the Indian economy.

Bauxite After silica, aluminum is the second highest abundant element present in the earth’s crust. However only 8% of the aluminum is present as the metallic element, with the remainder present as clay, soil and rocks that cannot be extracted. Bauxite is the only ore to be used in production of aluminum at an industrial scale. It is a heterogeneous ore that occurs naturally, and mainly consists of aluminous oxide minerals (gibbsite (Al2O3 ⋅ 3H2O), trihydrate, bohemite, diaspore (Al2O3 ⋅ H2O and monohydrates etc.), iron oxide (goethite & haematite), silica mineral (Kaolinite) & anatase TiO2 in traces. Commercial bauxites contain gibbsite and boehmite in larger quantities, and is rich in aluminum oxide (40–60%), iron oxide as Fe2O3 (7–30%), silica (1–15%), TiO2 (3–4%) and trace elements [6]. The majority of bauxite (80%) produced worldwide is being utilized in production of alumina using the Bayer process.

20,000

Types of Bauxite There are two major types of bauxite, lateritic and karst. Both are formed by weathering of parent rock, i.e. aluminosilicate rocks and interbedded carbonate. The lateritic bauxite is composed of gibbsite as aluminous mineral, kaolinite as silicate mineral and goethite iron mineral. It is formed by leaching of silica from aluminosilicate rock. Lateritic bauxite is classified into six major types on the basis of conditions of weathering and deposit age [7]. The karst bauxite is composed of boehmite and diaspore as aluminous mineral and kaolinite as silicate mineral. The karst bauxite is widely distributed in Northern Asia and Eastern Europe. The differences in composition of both bauxites are the result of different weathering conditions [8]. These compositional differences influence the processing methods required using the Bayer process, with the lateritic bauxite more easily digested compared to the karst bauxite.

Beneficiation In low-grade ores and run-of-mine (ROM), minerals are mostly associated with different impurities in the bauxite. The major impurities present in bauxite are silicon, iron oxides, and calcium, which introduces processing problems that can affect its utilizations in ceramics, abrasives and refractories [9]. Removal of these mineral impurities is required prior to the extraction of the desired mineral. Beneficiation can be defined as the process of improvement of the ore through the removal of different mineral impurities present. The two major steps of beneficiation are comminution and concentration [10]. The process of progressive

Advances in Beneficiation of Low-Grade Bauxite

particle size reduction of ore is known as comminution which is accomplished by crushing and grinding. Comminution is followed by concentration to increase the metal percentage in the ore by removal of gangue minerals. Mineral concentration is achieved by different methods such as gravity separation, magnetic separation, froth flotation, etc.

Bauxite Beneficiation The Bayer process is a well-established process for alumina extraction from bauxite, which makes use of caustic soda at high temperature. This method not only dissolves alumina but also reactive silica that is present in the ore, resulting in a higher consumption of caustic soda. For this reason an Al/Si ratio greater than 10 is considered to be best for use in the Bayer process. The presence of iron and calcium impurities in bauxite also introduces difficulties in its utilization in abrasives, ceramics, and refractories [11]. Different methods of beneficiation are being used to reduce the amount of silica, iron and calcium impurities in bauxite. Here both physicochemical as well as biotechnological methods of bauxite beneficiation are discussed.

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leading to increase in alumina content with a decrease in iron and silica content.

Magnetic Separation The magnetic separation technique involves separation of different minerals depending upon their magnetic property. Historically this technique was used to separate magnetic iron from gangue minerals. This technique now has wide application in various mineral processing industries, including the separation of silicate from manganese, and the separation of ferromagnetic and feebly magnetic material from diamagnetic material, etc. During the benefication of bauxite, removal of iron impurities is achieved by magnetic separation technique. After drying and calcination the bauxite is subjected to magnetic separation. Dey et al. [13] performed the beneficiation of low-grade bauxite using magnetic separation for its use in refractories. Rao et al. [12] studied the effect of pre-treatment in separating ferruginous impurities from bauxite by magnetic separation technique.

Froth Flotation Manual Breaking and Sorting Manual breaking and sorting by hand-picking are being employed to minimize the impurities in bauxite. The sorted bauxite lumps must not exceed 200 mm. Lumps of smaller size (10–25 mm) can be recovered by a fork-type hand shovel.

Mechanized Crushing and Grinding In high production mining the bauxite is subjected to mechanized crushing and grinding before the beneficiation process. This is the highest energy consuming and cost intensive process. Many attempts are made to reduce the energy consumption as well as the operation cost such as using additives while grinding, modification of machinery and heat shock treatment [12].

Screening, Scrubbing and Sashing After crushing, the bauxite need to be separated from the impurities. Separation is achieved by screening, scrubbing and washing. Mining industries make use of various screening equipments such as grizzles, stationary screens, vibrating screens etc. Rao and Das [11] carried out bauxite scrubbing in a batch scrubbing unit for 5 and 7.5 min,

Mining industry make use of froth flotation process to selectively separate different minerals. This process is meant to separate hydrophobic and hydrophilic materials. After crushing and grinding, the ore is mixed with water to produce a slurry to which specific collector chemicals are added to make the desired mineral hydrophobic. The slurry is then introduced into the bottom of the column to generate bubble. The hydrophobic mineral particles get attached to the bubble and rise to the surface as froth, which is then removed from the column. Froth flotation is reported to be the effective process in increasing the Al:Si ratio of low grade bauxite [14–21]. Anionic collectors are considered to be best for direct flotation [22] and cationic collectors are used in reverse flotation technique [17, 23, 24]. Different types of depressant (sodium silicate, starch) are used in the flotation method to depress the silicate and iron impurities present in bauxite [22]. The use of dispersants (sodium carbonate, sodium hexametaphosphate) in this process enhances the activity of the collector reagent [25]. To desilicate bauxite ores, direct flotation is considered the most effective method. But some difficulties are associated with this process such as dewatering of concentrates and high reagent utilization [26]. However, desilication of bauxite by reverse froth flotation using cationic collectors minimizes the operational cost and consumption of collectors, achieves a more efficient removal of gangue minerals, and displays easier dewatering [16, 27–35]. Xin-yang et al. [26] carried out reverse flotation of low grade bauxite using a cationic organosilicon surfactant, TAS

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L. B. Sukla et al.

101 (collector) and starch (depressant). They successfully eliminated silicate, thereby increasing the Al:Si ratio from 6.21 (low grade bauxite) to 9.85. Al2O3 recovery was reported at up to 83.34%. Kurusu et al. [36] successfully separated silicate impurities from mine tailing using the reverse froth flotation. They used amine and starch respectively as promoter and depressant at pH 10.0 for the silica removal.

Bio-beneficiation The conventional processes of metal beneficiation are expensive, energy-intensive and create environmental challenges [2]. Utilization of microbial consortia for beneficiation of bauxite is economically viable and environment friendly. Bio-beneficiation is described as the selective removal of undesired minerals from an ore by using microorganisms, resulting in the enrichment of the desired mineral constituent of the ore. Processes involved in microbial mineral beneficiation are selective leaching, flotation and flocculation [9]. Microbe-mineral interactions have shown better results in many works related to mineral beneficiation. The microbial beneficiation process has been described in beneficiation of iron ores, bauxite, limestone, and complex multi-metal sulfides. Numerous laboratory experiments suggested that microorganisms could play a similar role as that of conventional reagents in mineral beneficiation [37]. However, biological methods of mineral beneficiation by selective dissolution of impurities have received very little attention. A list of bacterial and fungal isolates from Western Indian bauxite deposits (Table 2) has demonstrated efficient removal of calcium and iron from bauxite. A large number of autotrophic and heterotrophic microbes were involved in bio-beneficiation processes, such as simple prokaryotes (bacteria and archaea) and complex eukaryotes (fungi). However, the functions of only a few bacteria (Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Desulfovibrio and Paenibacillus polymyxa) in beneficiation have been studied in detail [9]. Chemolithotrophic microorganisms are the first choice of several researchers for the bio-beneficiation process as they use inorganic compounds or minerals of the ore as the source of energy. However, the strains of Acidithiobacillus are mostly being used due to their capacity to oxidize sulfur and ferrous Table 2 The capability of bacterial and fungal isolates from Western Indian bauxite deposits in efficient removal of calcium and iron [41, 66]

compounds [37]. Various laboratory experiments make use of heterotrophic microbes for beneficiation of ores [67]. Various laboratory experiments reported the effective use of bacterial and fungal strains in removing iron and silica from the bauxite [39, 40]. Mostly the Bacillus species have been found to be effective for beneficiation of bauxite. Different water samples collected from the bauxite mines located in Jamnagar, India were studied for the existence of different microorganisms and their role in removal of iron and calcium from the bauxite. The results of this study revealed the occurrence of various heterotrophic bacteria, including Bacillus coagulans, Bacillus polymyxa and some fugal species [41]. Bacillus polymyxa is considered to be the most important microorganism in terms of its capability to remove iron, calcium and silica from bauxite. Aspergillus niger was reported to solubilize aluminum from aluminosilicates [42]. Fungal strains such as Aspergilus niger and Penicillium simplicisimum are reported to bring about aluminum leaching from bauxite [43, 44].

Mechanism Involved in Bio-Beneficiation of Bauxite It is evidenced that metal-microbe interaction brings about beneficiation of different metals by three major mechanisms, including adherence of microbes on the ore matrix, surface modification by the microbial activities, and biochemical reaction with the metabolic products produced during the microbial metabolism [37]. The metabolic products secreted by microorganisms that assist in beneficiation are shown in Table 3. The microoganisms enabling different roles in the bauxite beneficiation are shown in Table 4. Anand et al. [41] studied the possible mechanisms of removing iron and calcium from bauxite by biological means and suggested that the beneficiation process is brought about by both direct and indirect mechanisms. Direct mechanisms involve the attachment of microbial cells to the ore matrix as an important phenomenon to bring about surface modification of the ore. The extracellular polymeric substances of the microorganism ensure its attachment and selective removal of iron and calcium from the bauxite. The extracellular polysaccharides present on the microbial cell surface are very effective for the chelation of calcium and iron. According to Ehrlich et al. [45] and Friedrich et al. [46], there are three types of mechanism involved in microbial

Isolated microbes

% Ca removal

% iron removal

Paenibacillus polymyxa

86

26

Bacillus circulans

88

21

Pseudomonas spp.

83

33

Aspergillus fungi

78

15

Advances in Beneficiation of Low-Grade Bauxite Table 3 Metabolic products secreted by microorganisms helping in beneficiation [37]

Table 4 Microoganisms and their role in bauxite beneficiation

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Microorganisms

Major metabolic products

Pseudomonas sp.

Citric, oxalic and gluconic acids

Bacillus polymyxa

Acetic acid

Bacillus circulans

Succinic, formic, fumaric and maleic acids

Bacillus mucilaginosus

Exopolysaccharides

Thiobacillus sp.

Sulfuric acid, proteins

Aspergillu niger

Citric, oxalic and gluconic acids

Penicillium sp.

Citric and oxalic acids

Bacillus sp.

Amino acids

Yeast and algae

Protein and nucleic acids

Microorganisms

Role in beneficiation of bauxite

References

Bacillus circulans

Removal of silica from low grade bauxites

[58, 62]

Bacillus mucilaginosus

Removal of silica from bauxite

[38, 59, 62]

Bacillus edaphics

Removal of silica from bauxite

[62]

Paenibacillus polymyxa

Selective removal of calcium and iron from bauxite

[41, 56]

Aspergillus niger

Removal of iron oxides

[63]

Desulfuromonas palmitatis

Removal of iron oxides

[64]

interaction with the silicates, such as complete destruction of silicate lattice, dissolution of silicon by bacterial metabolism, and removal of silicon by acidolysis. Dissolution of silicate is associated with the activities of metabolic products produced by the microbes which may break the Si–O bond or act as the chelating agent [47, 48].

metabolites in the second step [41, 54]. Investigation on calcium removal through the cascade mode of column bioleaching shows efficient removal of calcium (>90%) [55, 56].

Removal of Silica Removal of Calcium The bacterium Bacillus polymyxa are known to play an important role in removal of impurities like calcium and iron from the low-grade bauxite [41]. It is a chemoorganotrophic, facultative anaerobe which produces various metabolites including lactic acid, formic acid, acetic acid, succinic acid, ethanol, etc. [38, 49–51]. The capsule of Bacillus polymyxa is formed by the extra-cellular polysaccharides (ECP) that are produced metabolically and acts as an effective chelating agent for iron like metals [41, 52]. Organic acids (acetic acid and lactic acid) are produced by fermentation under oxygen limiting conditions. Furthermore B. polymyxa facilitates the dissolution of iron by reducing ferric iron to ferrous. The bacterium requires calcium for its metabolism [49, 53]. It uses calcium present in the ore for the production of diffident metabolites like polysaccharides, organic acids, etc. which significantly dissolve iron from the bauxite. Hence the removal of calcium and iron takes place in such as way that in the initial step calcium is ingested by bacteria for the metabolism followed by the chelation of iron by the bacterial

In low-grade bauxites aluminosilicate is a major impurity. Silicate bacteria are known to have ability to leach silicon from silicate and aminosilicate minerals [57]. Bacillus circulans and Bacillus mucilaginosus were suggested to remove silica from bauxite [58, 59]. Groudeva et al. [58] performed a continuous leaching of silica for a duration of five days. Silicon removal from five different bauxite ore was examined by using both wild and laboratory-bred mutant strains of Bacillus circulans and Bacillus mucilaginosus. They used Ashby’s basal mineral salt medium with 2% sucrose as leaching solution. They reported that the silica removal increased from 12.5 to 73.6% as a result the Al:Si ratio of the ore increased significantly [38]. Silicate bacteria can be used to remove silica from bauxite in order to increase the Al2O3/SiO2 ratios [60]. The removal rate of silicon by silicate bacteria were different for different minerals such as bauxite, quartz and feldspar, which were reported at approximately 60, 40 and 30% respectively [61]. The rate of silicon removal from bauxite by leaching using three strains silicate bacteria (Bacillus circulans, Bacillus mucilaginosus and Bacillus edaphics) were examined in a

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single and cooperative bioleaching process. It was reported that the accordance of three strains with the ratio of 2:2:1 results in high rate of silicon leaching than in individual leaching process [62].

Removal of Iron Using iron-reducing bacteria shows effective results in removal of iron impurities from bauxite [60]. Several fungal species are known to produce organic acids which accounts for the reduction of iron. Papassiopi et al. [63] studied the studied the effect of organic acids (oxalic and citric acid) produced by the metabolism of Aspergillus niger on removal of iron oxides from bauxite ore. In this study oxalic and citric acids were produced by fermentation of a medium composed of sucrose by fungus Aspergillus niger. The leaching capacities of these fungal-produced organic acids were examined on bauxite sample which contained 16–19% of iron. The process of leaching using fungal-produced organic acids as a leaching solution results in removal of 80% of total iron from bauxite [63]. Papassiopi et al. [64] investigated the combined effect of ethylenediamine tetracetic acid (EDTA) and metabolism of Desulfuromonas palmitatis in removing iron oxides from the bauxite. The investigation was carried out on six samples of the bauxite which contained 16–22% of Fe2O3. The experiment resulted in 7–29% of iron removal from bauxite with the most rapid and highest extraction found in chamosite, a ferrous-rich compound. The interface of microbe-metal interaction and its manipulation has remained unexplored [65]. Therefore further work should be focused on the study of interfacial phenomenon, designing and manipulation of the biotic interfaces to solve existing challenges associated with commercialization of bio-beneficiation process [37]. Research is also necessary to establish optimized conditions for the growth and development of microorganisms to enhance the removal of impurity.

Conclusions Different impurities in bauxite make it incompatible to the aluminum industries as they develop poor binding property in the alumina grains. Therefore, removal of the impurities is necessary for the effective production. There are some physicochemical methods such as, breaking and sorting, crushing and grinding, screening, scrubbing and washing, magnetic separation, and froth flotation, have been successfully used for the removal of the impurities present in bauxite. However, these methods have been criticized by different scientific and technological communities. In this

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context, bio-beneficiation has proved the suitability. A wide variety of microorganisms are known to dissolve silica, iron and calcium present in the bauxite. The bio-beneficiation of bauxite is facilitated by three major mechanisms including adherence of microbes on the ore matrix, surface modification by the microbial activities, and biochemical reaction with the metabolic products produced during the microbial metabolism. However, an integrated pilot scale study must be experimented for the evaluation of all merits and de-merits before the commercial implementation, which requires details research and sustainable development. Acknowledgements The authors are grateful to Prof. (Dr.) Manojranjan Nayak, President, Siksha ‘O’ Anusandhan (Deemed to be University), for providing infrastructure and encouragement throughout.

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9 37. Rao KH, Vilinska A, Chernyshova IV (2010) Minerals bioprocessing: R & D needs in mineral biobeneficiation. Hydromet. 104: 465–470. 38. Groudev SN, Groudeva VI (1986) Biological leaching of aluminium from clays. Biotechnol. Bioeng. Symp. 16: 91–99. 39. Karavaiko GI, Belkanova NP, Eroshchev-Shak VA, Avakyan ZN (1984) Role of microorganism and some physic-chemical factors of the medium in quartz destruction. Microbiology 53: 795–800. 40. Ogurtsova LV, Karavaiko GI, Avakyan ZA, Korenevskii AA (1990) Activity of various microorganisms in extracting elements from bauxite. Microbiology 58: 774–780. 41. Anand P, Modak JM, Natarajan KA (1996) Biobeneficiation of bauxite using Bacillus polymyxa: calcium and iron removal. Int. J. Miner. Process. 48: 51–60. 42. Groudev SN, Genchev FN, Groudeva VI (1982) Use of microorganisms for recovery of aluminium from aluminosilicates: Achievements and prospects. Travaux ICSOBA 12-17: 203–212. 43. Ambreen N, Bhatti TM (2002) Bioleaching of bauxite by Penicillium simplicissimum. Online Journal of Biological Sciences 2: 793–796. 44. Ghorbani Y, Oliazadeh M, Shahverdi AR (2009) Microbiological leaching of Al from the waste of Bayer Process by selective fungi. Iranian Journal of Chemistry and Chemical Engineering 28: 109–115. 45. Ehrlich H, Demadis KD, Pokrovosky OS, Koutsoukos PG (2009) Modern views on desilification: biosilica and abiotic silica dissolution in natural and artificial environments. Chemical reviews 8:4656–4689. 46. Friedrich SNP, Platonova GI, Karavaiko E, Stichel, Glombitza F (1991) Chemical and microbiological soluiblization of silicates. Acta. Biotech. 11: 187–196. 47. Duff RB, Webley DM, Scott RO (1963) Solubilization of minerals and related materials by 2-ketogluconic acid-producing bacteria. Soil Science 95: 105–114. 48. Webley DM, Duff RB, Mitchell WA (1960) A plate method for studying the breakdown of synthetic and natural silicates by soil bacteria. Nature 188: 766–767. 49. Gottschalk, G (1989) Nutrition of bacteria. In: Starr, MP (ed) Bacterial Metabolism, Springer, New York, p 1–10. 50. Mankad T, Nauman EB (1992) Effect of oxygen on steady state product distribution in Bacillus polymyxa fermentations. Biotechnol. Bioeng. 40: 413–426. 51. Roberts JL (1947) Reduction of ferric hydroxide by strains of Bacillus polymyxa. Soil Sci. 63: 135–140. 52. Murphy D (1952) Structure of levan produced by Bacillus polymyxa. Can. J. Chem. 30: 872–878. 53. Wilkinson JF (1958) The extracellular polysaccharides of bacteria. Bact. Rev. 22:46–73. 54. Ash C, Priest FG, Collins MD (1993) Molecular identification of rRNA Group 3 Bacilli using a PCR probe test. Antonie van Leeuwenhoek 64: 253–260. 55. Modak JM, Vasan SS, Natarajan KA (1999) Calcium removal from bauxite using Bacillus polymyxa. Miner. Metall. Process 16: 6–12. 56. Vasan SS, Modak JM, Natarajan KA (2001) Some recent advances in the bioprocessing of bauxite. Int. J. Miner. Process. 62: 173– 186. 57. Aleksandrov VG, Zak GA (1950) Aluminosilicate destroying bacteria (silicate bacteria). Microbiologiya 19:97–104. 58. Groudev, SN et al. (1983) Removal of iron from sands by means of microorganisms. Progress Biohydrometall. 441–450. 59. Karavaiko, GI, Avakyan, ZA, Ogurtsova, LV, Safanova, OF (1989) Microbiological processing of bauxite. In: Salley, J, McGready, RGL, Wichlacz, L (eds), Proc. Biohydrometallurgy, CANMET, Ottawa, p 93–102.

10 60. Groudev AN (2001) Biobeneficiation of mineral raw materials. In: Kawatra, SK, Natarajan, KA (eds) Mineral Biotechnology, SME, Littleton, p 37. 61. Sun D, Wan Q, Zhan X (2008) Study on the Conditions of Silicon Release by Strain JXF of Silicate Bacteria. Mining Research and Development 3: 34–37. 62. Zhan S, Liu J, Chen Y, Sun D (2013) Single and Cooperative Bauxite Bioleaching by Silicate Bacteria. IERI Procedia 5: 172 – 177. 63. Papassiopi, N, Vaxevanidou, K, Paspaliaris, I, Katapodis, P, Kekos, D (2006) Iron removal from bauxite ores using biologically produced organic acids. Presented at the 2nd International Conference on Advances in Mineral Resources Management and Environmental Geotechnology (Amireg), p 275–280.

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Leaching Kinetics of Thermally-Activated, High Silica Bauxite Hong Peng, Steven Peters, and James Vaughan

Abstract

Thermal activation of bauxite has been proposed to enable removal of organic carbon and reducing boehmite digestion temperature. However, there is limited published research about how thermally activated bauxite behaves at pre-desilication (8 %) and an A/S ratio of less than 6 are currently considered to be uneconomic to treat with the conventional Bayer process [3]. Many approaches have been proposed to upgrade bauxites, for example by screening, flotation, magnetic separation and thermo-chemical methods based on the physical and chemical properties of ores [4–6]. For bauxites with fine grain sizes and lower degrees of liberation, thermo-chemical methods have been proposed for effective pre-desilication. This method focused on the thermal transformation of kaolinite into amorphous silica via formation of metakaolin with a temperature over 1000 °C [4, 7]. Thermal activation of bauxite can also remove organic carbon [8] or convert boehmite to intermediate alumina phases enabling low temperature digestion in the processing of the bauxite [9, 10]. Recently, a comprehensive investigation of thermal activation on dissolution of kaolinite by metakaolinization has been reported [11]. The results indicated that the dissolution of metakaolin at a temperature of 90 °C is fast. Within a short period of 30 min almost all silica in the solids could be dissolved into solution without the formation of DSP. Another investigation showed the profile of

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dehydroxylation of kaolinite and other components of the bauxite with increasing temperature using in situ XRD [12]. By heating at 650 °C for 30 min, gibbsite, boehmite and kaolinite in the bauxite were transformed into amorphous phases. This report builds on that research to investigate the leaching kinetics of thermally activated bauxite compared with the original bauxite at the low pre-desilication temperature of 70 °C in synthetic solutions at two sodium hydroxide concentrations (4 M and 8 M). A new desilication procedure is proposed that combines thermal activation with low temperature leaching for short residence times. Using this approach, the A/S ratio is increased from 2.75 to 7.3.

Experimental Materials and Reagents The bauxite samples were provided by external industry partners. Sodium hydroxide pellets (98%) and aluminum hydroxide powder (99.4%) were sourced from Sigma-Aldrich. Concentrated solutions of up to 12 M NaOH were prepared by dissolving analytical grade chemicals in DI water (1000 °C) roast with additional reagents in the form of Na2CO3 or CaCO3 for extraction [22]. During this method, the liberation of iron

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can also promote the formation of sodium ferrites, which cause significant processing difficulties through reactions to yield various insoluble compounds [23]. The viability of residue reprocessing is influenced by the reactive silica content in the feed bauxite. If sufficiently high, DSP phases will contribute to a large component of the final residue, leading to significant Na and Al losses. BR5 contained both the highest concentration of DSP among the analysed residues, as well as no or insignificant amounts of aluminium substituted within the iron oxides. These properties make this residue a good target for the recovery of soda and alumina once the economic trade-off is met, as the Na2O and Al2O3 lost with the 26.8 wt% DSP can be recycled directly into the Bayer process. Assuming that alumina in the form of DSP and aluminium hydroxides can be recovered through process improvements and/or recycling, an order can be provided on the feasibility of recovering aluminium from the residues: BR1 [ BR5 [ [ BR3 [ BR2  BR4

Conclusion Bauxite residue management is quickly becoming a major priority for the bauxite and aluminium industry, as there has been increased pressure to move towards sustainability in recent years. This has been the main driving force for research into bauxite residue reprocessing and recycling. Analysis showed that in the majority of samples, a high degree of Al-for-Fe substitution was found. BR1 and BR5 are examples of residues that may be most suitable for Al and Na metal recovery through process optimisations, or methods such as sinter-leach. Moving forward, modelling of a new SOD structure that can accurately describe the SOD (310) peak is recommended to further improve quantification. Accounting for the incorporation of other metals into the structure of iron oxides in bauxite residue is another aspect that can be included in future analysis, as this study only considers a Fe-Al solid solution. Undertaking advanced characterisation with quantitative XRD, particularly on the Al and Na bearing phases, can aid significantly in determining which bauxite residues are indicators for potential process improvements. Acknowledgements The authors acknowledge the funding provided by the Alumina Quality Workshop (AQW Inc.) postgraduate scholarship. This research was supported by funding from ARC Linkage project LP160100207 and the International Aluminium Institute. This research was undertaken on the Powder Diffraction (10BM1) beamline at the Australian Synchrotron, part of ANSTO. This research was also undertaken on the Powder Diffraction (BL14B1) beamline at the Shanghai Synchrotron Radiation Facility.

References 1. International Aluminium Institute, Bauxite residue management: Best practice. 2015. 2. Power, G., M. Gräfe, and C. Klauber, Bauxite residue issues: I. Current management, disposal and storage practices. Hydrometallurgy, 2011. 108(1): p. 33–45. 3. Santini, T.C. and M.V. Fey, From tailings to soil: long-term effects of amendments on progress and trajectory of soil formation and in situ remediation in bauxite residue. Journal of Soils and Sediments, 2018. 18(5): p. 1935–1949. 4. Evans, K., Successes and challenges in the management and use of bauxite residue, in Bauxite residue valorisation and best practices. 2015: Leuven. p. 113–128. 5. Santini, T.C. and M.V. Fey, Fly ash as a permeable cap for tailings management: pedogenesis in bauxite residue tailings. Journal of Soils and Sediments, 2015. 15(3): p. 552–564. 6. Cheary, R.W. and A. Coelho, A fundamental parameters approach to X-ray line-profile fitting. Journal of Applied Crystallography, 1992. 25(2): p. 109–121. 7. Hill, R.J. and C.J. Howard, Quantitative phase analysis from neutron powder diffraction data using the Rietveld method. Journal of Applied Crystallography, 1987. 20(6): p. 467–474. 8. Whittington, B. and T. Fallows, Formation of lime-containing desilication product (DSP) in the Bayer process: factors influencing the laboratory modelling of DSP formation. Hydrometallurgy, 1997. 45(3): p. 289–303. 9. Schulze, D.G. and U. Schwertmann, The influence of aluminium on iron oxides: X. Properties of Al-substituted goethites. Clay Minerals, 1984. 19(4): p. 521–539. 10. Trolard, F. and Y. Tardy, The stabilities of gibbsite, boehmite, aluminous goethites and aluminous hematites in bauxites, ferricretes and laterites as a function of water activity, temperature and particle size. Geochimica et Cosmochimica Acta, 1987. 51(4): p. 945–957. 11. Li, D., et al., Mineralogy of Al-substituted goethites. Powder Diffraction, 2006. 21(4): p. 289–299. 12. Neumann, R., A.N. Avelar, and G.M. da Costa, Refinement of the isomorphic substitutions in goethite and hematite by the Rietveld method, and relevance to bauxite characterisation and processing. Minerals Engineering, 2014. 55: p. 80–86. 13. Schwertmann, U. and L. Carlson, Aluminum influence on iron oxides: XVII. Unit-cell parameters and aluminum substitution of natural goethites. Soil Science Society of America Journal, 1994. 58(1): p. 256–261. 14. Wu, F., Aluminous goethite in the bayer process and its impact on alumina recovery and settling, in Department of Chemistry. 2012, Curtin University. 15. Li, W., et al., Mechanisms on the morphology variation of hematite crystals by Al substitution: The modification of Fe and O reticular densities. Scientific Reports, 2016. 6: p. 35960. 16. Dunyushkina, L.A. and V.A. Gorbunov, Effect of crystal structure on the electrical properties of CaTi1 – xFexO3. Inorganic Materials, 2001. 37(11): p. 1165–1169. 17. Riley, G., et al., Plant Impurity Balances and Inclusion in DSP, in Fifth International Alumina Quality Workshop. 1999, AQW Incorporated: Bunbury, Western Australia. p. 404–414. 18. Vogrin, J., et al., Characterisation and steps toward structure solution of synthetic anion-substituted desilication products, in Alumina 2018. 2018: Gladstone, Australia. p. 233–240. 19. Balassone, G., et al., Sodalite-group minerals from the Somma – Vesuvius volcanic complex, Italy: a case study of K-feldspar-rich xenoliths. Mineralogical Magazine, 2012. 76(1): p. 191–212.

Quantitative X-Ray Diffraction Study into Bauxite Residue … 20. Kanepit, V.N. and E.É. Rieder, Neutron diffraction study of cancrinite. Journal of Structural Chemistry, 1995. 36(4): p. 694– 696. 21. Peng, H., et al., Advanced characterisation of bauxite residue, in Alumina 2018. 2018: Gladstone, Australia. p. 189–195.

99 22. Li, G., et al., Beneficiation of high-aluminium-content hematite ore by soda ash roasting. Mineral Processing and Extractive Metallurgy Review, 2010. 31(3): p. 150–164. 23. Qi, T., et al., A review of the bauxite residue sinter-leach process, in Alumina 2018. 2018: Gladstone, Australia. p. 181–188.

Technospheric Mining of Rare Earth Elements and Refractory Metals from Bauxite Residue John Anawati and Gisele Azimi

Abstract

For moving towards a sustainable future and building the circular economy, there is a push towards waste valorization. Bauxite residue is the by-product of the Bayar process for alumina production. It contains considerable amounts of rare earth elements (REEs) and refractory metals, some of which are considered critical materials and initiatives have begun to mine them from secondary sources, such as landfilled industrial process residues. Here, we develop a novel pyro-hydrometallurgical process called acid-baking water-leaching to extract REEs and refractory metals from bauxite residue. In this process, bauxite residue is mixed with concentrated sulfuric acid, baked at 200–400 °C, and leached in water at ambient conditions. Compared with conventional hydrometallurgical processes, the developed process offers the advantages of less acid consumption, less wastewater generation, and fast kinetics. Work is currently underway to develop this promising technique as the first step of a potential near-zero-waste integrated process for the sustainable valorization of bauxite residue. Keywords








Rare earth elements Refractory metals Acid baking water leaching Waste valorization

J. Anawati
G. Azimi (&) Laboratory for Strategic Materials, Department of Chemical Engineering and Applied Chemistry, 200 College Street, Toronto, ON M5S 3E5, Canada e-mail: [email protected] G. Azimi Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, ON M5S 3E4, Canada

Introduction In recent years, there has been an increased interest in the sustainable sourcing of materials and management of waste products in most industries, in particular the materials and metals sector. The reason behind this push is concerns in the reliable supply of critical materials and broader appreciation of the environmental impacts of these processes. Within this context, the aluminum industry, and bauxite residue in particular, offers an exciting opportunity for the synergistic extraction and recovery of valuable materials, and the benefaction of an otherwise waste material [1]. Bauxite residue (BR, sometimes referred-to as red mud) is the solid side-product of the Bayer process for the production of aluminum oxide (Al2O3), an important intermediate in the primary production of aluminum metal from bauxite ore. It is a minerallogically-complex mixture of iron and aluminum oxides and hydroxides, calcium-titaniumaluminum silicates, and sodium hydroxide [2, 3]. On a dry solids basis, between 0.7 and 2 tonnes of BR are produced for each tonne of Al2O3 production [4]. Since the annual worldwide primary production of aluminum is 60 million tonnes, roughly 150 million tonnes of new BR are produced annually, resulting in a worldwide stockpile of approximately 3 billion tonnes [5, 6]. Because of its complexity, high production volume, and high alkalinity (pH 10–13), the current common industry practice of BR management is landfilling in dry heaps or tailing ponds. Only 3% of current global reserves are employed productively, primarily as an additive in the production of cements [6]. As a material with abundant supply and near-zero demand, BR represents a promising feedstock candidate for value-added processes. One potential valorization opportunity for BR is its use as a secondary resource for the recovery of valuable materials, including scandium (Sc), rare earth elements (REEs), titanium (Ti), and other refractory metals (Nb, Hf, Zr).

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Several studies examining hydrometallurgical and pyrometallurgical techniques for the extraction of metals from BR have been conducted in the past, with the majority of work employing direct acid leaching of the residue in dilute mineral acids (H2SO4, HNO3, HCl) followed by subsequent purification using solvent extraction, selective precipitation or ion exchange [1, 7, 8]. While being a well-understood process, the direct leaching pathway possesses some disadvantages, including low-to-moderate extraction efficiencies, large consumption of water, acids, and organic solvents, poor selectivity for the target materials, the formation of problematic silica gels, and the formation of high volumes of hazardous waste [9]. In this work, an alternative hybrid pyro-hydro-metallurgical process, employing acid-baking water-leaching (ABWL), was developed to address the shortcomings of direct leaching, in particular to improve the extraction efficiencies, to reduce the consumption of acids and water, and to prevent the formation of silica gels.

The ABWL Process ABWL is a hybrid pyro-hydro-metallurgical process, employed primarily in the processing of REE ores, which comprises three main steps, and associated preparation steps (Fig. 1): 1. Collection of filter-pressed bauxite residue (*29 wt% moisture) 2. Drying the bauxite residue for 24 h at 50 °C 3. Crushing the dried BR to a powder. In the laboratory, this is carried-out manually with a mortar and pestle

Fig. 1 Illustration of the ABWL process. At the laboratory scale. Representative photographs of the various processing steps are shown. Photo Source Anawati and Azimi

J. Anawati and G. Azimi

4. Dry digestion (digestion without the addition of water) of crushed minerals in concentrated sulfuric acid (95% H2SO4). 5. Heat treatment at high temperatures (200–400 °C), for 1– 2 h. 6. Water leaching at ambient temperature (*25 °C) and pressure. In contrast to conventional leaching, ABWL allows greater control of the extraction conditions, allowing the physicochemical environment to be specifically tuned to enhance the different aspects of the extraction mechanism and enhance the process economics. In essence, the leaching reaction can be separated into two separate phenomena, the acid digestion and sulfation of the BR minerals and the water solvation of these resulting sulfate species. The ABWL process enables the separation of these processes into two distinct steps with separate optimal conditions. The acid digestion step, in which the BR matrix minerals are broken down and converted to soluble species to release the valuable materials, benefits from the direct dry digestion at high temperatures because the high acid concentration and temperature increase the digestion kinetic driving force, and the high acid concentration additionally acts to prevent the formation of soluble silica species, which are detrimental to downstream separations [10–12]. Furthermore, the high temperature has the advantage of evaporating the water produced in the acid digestion reactions, driving the equilibrium towards the products. The water leaching step can, in turn be optimized for process economics, operating at ambient temperature and pressure and short residence time.

Technospheric Mining of Rare Earth Elements and Refractory …

Results and Discussion Scandium (Sc) is one of the most valuable minor elements found in bauxite residue, with the oxide (Sc2O3, 99.99% purity) having a current value of US$1750/kg; [13] Canadian BR has a Sc content of 31 mg/kg. As such, this study focused on the Sc extraction trends. In BR, Sc is known to associate with Fe(III), with Sc extraction requiring the decomposition of the Fe(III)-oxide lattice (Fe2O3 and FeO (OH)), [14] as such Fe extraction and phase transformations was also monitored to provide insight into the behavior of the main Sc-bearing phases. Additionally, titanium (Ti) is a relatively valuable metal (US$8.60/kg), [13] which comprises 3.8 wt% of BR; thus, Ti extraction was also studied. Figure 1 compares the extraction of Sc, Fe, and Ti over time for three different acid-baking conditions: 25 °C (acid incubation at room temperature), 200, and 400 °C, for 2 h, given a fixed acid-to-BR ratio of 0:95 mLH2 SO4 =gBR , and a fixed water-to-ABBR ratio of 9:5 mLH2 O =gABBR . Extraction concentrations were determined by ICP-OES. To quantify the kinetic and saturation trends for the experiments, the extraction data was fit to the following second-order empirical kinetic leaching model: dCi ¼ k2 ðCsat  Ci Þ2 dt

ð1Þ

It was primarily evident that two different leaching mechanisms were observed, depending on the baking temperature utilized: at 25 and 200 °C, leaching was extremely rapid, with saturation being reached within 5 min of leaching for Sc, Fe, and Ti. The 200 °C treatment was shown to produce a distinct improvement in the leaching saturation concentration of all three elements, in particular Ti and Sc, without affecting the leaching kinetics. In contrast, baking at 400 °C had a strong

103

impact on leaching kinetics, slowing the extraction considerably—although with the benefit of strongly increasing the saturation concentration for Sc and Ti. These results suggest that two possible extraction mechanisms can occur during the ABWL process, depending on the baking temperature employed in the acid-baking step. In both cases, the Fe3+ ions are soluble in water as the residue pH is sufficiently low to prevent Fe(III) hydrolysis and precipitation [15]. The Ti solubilization can be explained by the formation of soluble titanyl sulfate (TiOSO4), which is formed when TiO2 is heated at elevated temperatures in H2SO4 [16] (note: the TiOSO4 was likely present in insufficient concentrations to permit identification via XRD); this transition can explain the lack of extraction observed for dry digestion at 25 °C, compared to the considerable extraction observed for the acid-baked samples (200–400 °C) (Fig. 2). The differences in the leaching mechanisms at different baking temperatures can be primarily attributed to changes in the main mineral phases formed—these phase differences were investigated by X-ray diffraction (XRD) analysis, as shown in Fig. 3 (in this figure, some of the major peaks associated with the primary phases of interest are highlighted, and the crystal structures for (H3O)Fe(SO4)2 [17] and rhombohedral Fe2(SO4)3 [18] are shown for reference). The primary Fe-bearing phases in the starting BR were FeO(OH) and Fe2O3—in all cases, a near-complete digestion of these phases was observed, with the Fe forming sulfate-bearing (SO42−) phases. At the lower baking temperatures (200–250 °C), the formation of oxonium double-sulfate phases ((H3O)Fe(SO4)2) were observed; however, with increasing baking temperature (  250 °C), the (H3O)Fe(SO4)2 phases decreased, being replaced by anhydrous iron-sulfate (Fe2(SO4)3) phases. (H3O)Fe(SO4)2 is a relatively unstable and highly hygroscopic derivative of rhomboclase ((H5O2)Fe(SO4)2̇ 2H2O), formed at conditions of high temperature, acidity,

Fig. 2 Comparison of Sc, Fe, and Ti extraction efficiencies following acid baking at 25, 200, and 400 °C, and water leaching at 25 °C. Data Source Anawati and Azimi

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J. Anawati and G. Azimi

Fig. 3 XRD diffractograms of the mineral phase changes occurring during acid baking. All samples were baked for 2 h with the indicated acid ratio and baking temperature. Data Source Anawati and Azimi.

The structures were visualized using VESTA software [19]. Reprinted from: Anawati [3]

and sulfate concentration, and low humidity [17, 20]. As shown in Fig. 3, it has a layered structure of Fe3+ and SO42− groups, separated by sheets of H3O+ ions, held together by weak hydrogen bonding. This structure has been shown to decompose to an amorphous material when moisture readily infiltrates within the layers and disrupts the hydrogen bonding [17]. At high temperatures, (H3O)Fe(SO4)2 converts to Fe2(SO4)3 according to Eq. 2.

release of additional H2SO4, which can further go on to react with unreacted matrix minerals; thus, increasing the overall release and extraction of valuable materials.

2ðH3 OÞFeðSO4 Þ2 ! Fe2 ðSO4 Þ3 þ 2H2 OðgÞ þ H2 SO4 ð2Þ In contrast to (H3O)Fe(SO4)2, rhombohedral Fe2(SO4)3 has a crystal lattice held together entirely by strong ionic bonding. These differences in the crystal lattice structures of these two primary phases can explain the observed differences in the leaching kinetics for the different baking temperatures. At the lower temperature (200 °C), the moisture-sensitive (H3O)Fe(SO4)2 readily decomposes, leading to rapid leaching, while the Fe2(SO4)3 found at the higher temperature (400 °C) ABBR does not decompose as-readily, leading to slower leaching kinetics. This phase transition can also explain the observed increase in saturation concentration at higher temperatures. As shown in Eq. 1, the transition from (H3O)Fe(SO4)2 to Fe2(SO4)3 results in the

Conclusions In summary, a hybrid pyro-hydro-metallurgical acid-baking water-leaching process to extract scandium, titanium, and other valuable materials from bauxite residue was developed. It was demonstrated that the addition of a 200–400 °C heat treatment step to H2SO4-digested BR results in enhanced Ti and Sc extraction on subsequent leaching in water at ambient temperature and pressure. It was also demonstrated that the leaching kinetics and saturation can be tuned, either to maximize saturation concentration or to minimize leaching duration, using the acid-baking temperature as a physicochemical switch between mineral phases with different leaching characteristics. This work supports a larger initiative to develop a sustainable near-zero-waste process for the valorization of bauxite residue. The ABWL process addresses some of the main challenges of direct acid leaching, mainly improving the extraction efficiencies of the target

Technospheric Mining of Rare Earth Elements and Refractory …

materials, reducing the consumption of acid and water, and preventing the formation of silica gels. Further work will focus on addressing the additional challenges of improving the leaching selectivity for the target materials, the separation of Sc from Fe in the leachate, and the re-use and management of all the waste streams originating from the process.

References 1. Binnemans, K.; Jones, P. T.; Blanpain, B.; Van Gerven, T.; Pontikes, Y. Towards Zero-Waste Valorisation of Rare-EarthContaining Industrial Process Residues: A Critical Review. Journal of Cleaner Production. Elsevier Ltd 2015, pp 17–38. 2. Liu, Y.; Naidu, R. Hidden Values in Bauxite Residue (Red Mud): Recovery of Metals. Waste Manag. 2014, 34 (12), 2662–2673. 3. Anawati, J. Innovative and Sustainable Valorization Process to Recover Scandium from Canadian Bauxite Residue. In Extraction 2018 - MetSoc Live Learning Center; Metallurgy and Materials Society of CIM: Ottawa, ON, 2018. 4. Reid, S.; Tam, J.; Yang, M.; Azimi, G. Technospheric Mining of Rare Earth Elements from Bauxite Residue (Red Mud): Process Optimization, Kinetic Investigation, and Microwave Pretreatment. Sci. Rep. 2017, 7 (1), 1–9. 5. The International Aluminium Institute. PRIMARY ALUMINIUM PRODUCTION - Global Data for Jan 1973 to Jan 2018; 2018. 6. Evans, K. The History, Challenges, and New Developments in the Management and Use of Bauxite Residue. J. Sustain. Metall. 2016, 2 (4), 316–331. 7. Borra, C. R.; Blanpain, B.; Pontikes, Y.; Binnemans, K.; Van Gerven, T. Recovery of Rare Earths and Other Valuable Metals From Bauxite Residue (Red Mud): A Review. J. Sustain. Metall. 2016, 2 (4), 365–386. 8. Boudreault, R., Fournier, J., Primeau, D. & Labrecque-Gilbert, M.M. Processes for Treating Red Mud, US Patent US20150275330, 2015. 9. Yagmurlu, B.; Dittrich, C.; Friedrich, B. Precipitation Trends of Scandium in Synthetic Red Mud Solutions with Different Precipitation Agents. J. Sustain. Metall. 2017, 3 (1), 90–98.

105 10. Rivera, R. M.; Ulenaers, B.; Ounoughene, G.; Binnemans, K.; Van Gerven, T. Extraction of Rare Earths from Bauxite Residue (Red Mud) by Dry Digestion Followed by Water Leaching. Miner. Eng. 2018, 119 (October 2017), 82–92. 11. Alkan, G.; Yagmurlu, B.; Ma, Y.; Xakalashe, B.; Stopic, S.; Dittrich, C.; Friedrich, B. Combining Pyrometallurgical Conditioning and Dry Acid Digestion of Red Mud for Selective Sc Extraction and TiO2 Enrichment in Mineral Phase. In Proceedings of the 2nd International Bauxite Residue Valorisation and Best Practices Conference; Pontikes, Y., Ed.; Athens, 2018; pp 215–222. 12. Alkan, G.; Yagmurlu, B.; Cakmakoglu, S.; Hertel, T.; Kaya, Ş.; Gronen, L.; Stopic, S.; Friedrich, B. Novel Approach for Enhanced Scandium and Titanium Leaching Efficiency from Bauxite Residue with Suppressed Silica Gel Formation. Sci. Rep. 2018, 8 (1), 1–11. 13. U.S. Geological Survey. Mineral Commodity Summaries 2018; 2018. 14. Borra, C. R.; Pontikes, Y.; Binnemans, K.; Gerven, T. Van. Leaching of Rare Earths from Bauxite Residue (Red Mud). Miner. Eng. 2015, 76, 20–27. 15. Marcus, P.; Protopopof, E. Potential-PH Diagrams for Adsorbed Species - Application to Sulfur Adsorbed on Iron in Water at 25 and 300 C. J. Electrochem. Soc. 1990, 137 (9), 2709. 16. Gatehouse, B. M.; Platts, S. N.; Williams, T. B. Structure of Anhydrous Titanyl Sulfate, Titanyl Sulfate Monohydrate and Prediction of a New Structure. Acta Crystallogr. Sect. B 1993, 49 (3), 428–435. 17. Peterson, R. C.; Valyashko, E.; Wang, R. The Atomic Structure of (H3O)Fe3+(SO4)2 and Rhomboclase, (H5O2)Fe3+(SO4)2−2H2O. Can. Mineral. 2009, 47, 625–634. 18. Christidis, P. C.; Rentzeperis, P. J. The Crystal Structure of Rhombohedral Fe2(SO4)3. Zeitschrift für Krist. 1976, 144 (341– 352). 19. Momma, K.; Izumi, F. VESTA 3 for Three-Dimensional Visualization of Crystal, Volumetric and Morphology Data. J. Appl. Crystallogr. 2011, 44, 1272–1276. 20. Xu, W.; Parise, J. B.; Hanson, J. (H3O)Fe(SO4)2 Formed by Dehydrating Rhomboclase and Its Potential Existence on Mars. Am. Mineral. 2010, 95 (10), 1408–1412.

Migration of Iron, Aluminum and Alkali Metal Within Pre-reduced-Smelting Separation of Bauxite Residue Jian Pan, Siwei Li, Deqing Zhu, Jiwei Xu, and Jianlei Chou

Abstract

Bauxite residue (red mud) is a hazardous waste generated from alumina refining industries. Bauxite residue contains elevated concentrations of several elements, such as iron, aluminum, titanium and sodium. Due to the high concentration of sodium, the bauxite residue cannot be directly employed as a raw material for iron-making. In this work, the migration of iron, aluminum and alkali metal within a pre-reduced-smelting separation was investigated. The results showed that the content of iron, Al2O3 and Na2O in pig iron and slag are 94.07, 0.11% and 0.013, 9.23, 48.63 and 4.92%, respectively; effectively separating iron into the pig iron and aluminum and sodium into the slag. The obtained pig iron can be used as the burden for an electric arc furnace (EAF). Meanwhile, the slag can be leached by alkali leaching to extract aluminum and sodium. Keywords

Bauxite residue




Migration




Fe

Al

Na

J. Pan
S. Li (&)
D. Zhu
J. Xu
J. Chou School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, People’s Republic of China e-mail: [email protected] J. Pan e-mail: [email protected] D. Zhu e-mail: [email protected] J. Xu e-mail: [email protected] J. Chou e-mail: [email protected]

Introduction Red mud is a waste material, which is generated from the aluminum industry via the Bayer process and it mainly contains alumina, silica, iron oxides and soda [1]. Approximately 1–1.5 tons red mud is generated per ton alumina. Globally, nearly 120 million tons of red mud per year is produced, and it is estimated that the global residue storage will reach approximately 4 billion tons by 2015. With iron ore resources decreasing, the utilization rate of red mud for iron recovery has been increased. Moreover, due to the high alkalinity of red mud, the storage of red mud has posed a significant risk to the environment [2]. Therefore, it is advantageous to develop new methods to reuse red mud more effectively to deliver economic and environmental benefits. Comprehensive utilization of red mud has been extensively studied. Some of them involve the reuse of red mud as a raw material for iron making. The methods mainly contain direct magnetic separation [3], acid leaching [4–6], direction reduction-magnetic separation [7] and smelting separation [8]. Regardless of red mud types, overall recovery rate of iron was lower (28–35%) through the direct magnetic separation. Acid leaching mainly involved sulfuric acid leaching, hydrochloric acid leaching and oxalic acid leaching. Optimized 47% iron recovery was achieved at leaching conditions of 100 °C for 24 h, using 8 N sulphuric acid. Cengenloglu et al. adopted hydrochloric acid to treat the red mud and obtained 0.03–15.13% iron recovery. Yu et al. treated red mud using oxalic acid for iron recovery. The iron content of the red mud (12.31%) was reduced to

0.60 0.65 0.67 0.70 0.72 0.75 0.77 0.80 0.82 0.85 0.90 0.90

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%2 Concentration - 1-Alkaline Detergent

Fig. 6 Roughness changes on surface with alkali degreasing chemicals prepared in 2% concentration

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%3 Concentration - 1-Alkaline Detergent

Fig. 7 Roughness changes on surface with alkali degreasing chemicals prepared in 3% concentration

Bath Temperature ( C )

60

Ra 0.65 0.70 0.75 0.80 0.85 0.90

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< – – – – – – >

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Acidic Detergent Roughness Average Values

Fig. 8 Roughness changes on the surface with acidic degreasing chemicals

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Ra 0.60 0.65 0.67 0.70 0.72 0.75 0.77 0.80 0.82 0.85

Bath Temperature ( C )

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< – – – – – – – – – – >

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Similar results with dissolution behaviour according to temperature and duration in alkaline environment have similar results with the work of Prabhu et al. [9]. In Fig. 8, the roughness values (Ra) of the aluminium sheets contacted at different temperatures and immersion times in the acidic tanks and the roughness values observed higher.

observed that the roughness and wetting angle changes on the substrate surface did not affect the final painted products for powder coating. The effect of the interface properties on the coating resistance cannot be explained in the performed tests. Samples could be seen in Fig. 9 [9].

Conclusion Tested of Powder Coated Surface Properties The surfaces of the samples prepared according to different bath parameters are coated with electrostatic powder paint. When the paint performance tests were examined, it was

Changes in annealing temperatures and degreasing parameters of aluminum sheets caused changes in surface roughness and wetting angle values, and these changes were found to be strongly related to the surface oxide structure.

Characteristics of Surface Properties of Aluminum Flat Products …

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Fig. 9 Impact test result (a), Cupping test result (b), Cross-cut adhesion test result (c) [2]

(a) 1. It has been reported in the literature that aluminum surface oxides in the temperature range of 420 °C are transformed from amorphous Al2 O3 form to c-Al2 O3 form. This conversion value is confirmed by the surface roughness and wetting angle measurement results. 2. The surface tension and roughness values of the alloys were found to be proportional to the temperature. Roughness values of alloy 1050 are lower than values of alloy 3005. 3. The regression model summary data for surface wetting contact angle and annealing temperature are compatible. 4. Alkaline degreasing chemical has an inversely direct proportional relationship between bath reactivity and roughness value. 5. At the increasing of acidic degreasing chemical reactivity, roughness increases directionally. 6. For both alloys, it has been observed that the acidic and alkaline degreasing chemicals do not effect the adhesion, performance tests for powder coating at the relevant parameters. Future Works Electrochemical methods will give for more meaningful results for the interaction of the interface between powder coating and aluminium surface. It will investigate in future. Acknowledgements We would like to thank Sistem Aluminum company and their respectable staffs for their support during the painting of sheet and performance tests. Also thanks to Oktay Kuşlar

(b)

(c)

and Gökhan Ever and other all laboratory personnels of Teknik Aluminum for their earnest efforts.

References 1. J. Randolph and L. Ferry, Aluminum Structures: A guide to their specifications and design 2nd Edition, (2002) 23–24. 2. S. Wernick and R. Pinner, “The Surface Treatment and Finishing of Aluminum and It’s Alloys”, Robert Draper Ltd., Middleser England 11 (1956) 102–110. 3. F. P. Fehlne and, N. F. Mott, Low temperature Oxidation, Oxidation of Metals, 2 (1970). 4. L. Mummery, Surface Texture Analysis the Handbook, Hommelwerke GmbH, 1990 25–47. 5. E. N. Coker, The Oxidation of Aluminum at High Temperature Studied by Thermogravimetric Analysis and Differential Scanning Calorimetry, Sandia National Laboratories, 2013 7–9. 6. G. Litrico, P. Proulx, J. B. Gouriet, P. Rambaud, Controlled Oxidation of Aluminum Nanoparticles, Advanced Powder Technology 26 (2015) 1–7. 7. L. P. H. Jeurgens, W. G. Sloof, F. D. Tichelaar, E. J. Mittemeijer, Structure and Morphology of Aluminium-Oxide films Formed by Thermal Oxidation of Aluminum, The Solid films 418 (2002) 89– 101. 8. D. Prabhu and P. Rao, Corrosion Behaviour of 6063 Aluminum Alloy in Acidic and in Alkaline Media, Arabian Journal of Chemistry 10 (2017) 2234–2244. 9. S. Joshi, W. G. Fahrenholtz, M. J. O’Keefe, Effect of Alkaline Cleaning and Activation on Aluminum Alloy 7075-T6, Applied Surface Science 257 (2011) 1859–1863. 10. K.M. Wibowo, M.Z. Sahdan, M.T. Asmah, H. Saim, F. Adriyanto, Suyitno, S. Hadi, “Influence of Annealing Temperature on Surface Morphological and Electrical Properties of Aluminum Thin Film on Glass Substrate by Vacuum Thermal Evaporator”, IRIS (2017), 226–212.

Comparative Electrochemical and Intergranular Corrosion-Resistance Testing of Wrought Aluminium Alloys Varužan Kevorkijan, Lucija Skledar, Marko Degiampietro, Irena Lesjak, and Teja Krumpak









Abstract

Keywords

In this work the susceptibility to intergranular corrosion of (i) different wrought aluminium alloys and (ii) various compositions of the same standard alloy was investigated with electrochemical and metallographic methods. The main difficulty in predicting the intergranular corrosion behaviour based on the results of the electrochemical corrosion test is in the fact that, even when performed with the same chloride medium and under the same or similar experimental conditions, electrochemical fatigue results in a different corrosion attack on the surface of aluminium-based products. On the other hand, the measure of the intergranular corrosion is often under the operator’s influence, which is not the case in electrochemical corrosion testing. Therefore, the purpose of this study was to correlate the results of these two methods, enabling the accumulation of the appropriate filtered and structured data for high-quality data-driven predictions of the most stress-corrosion-resistant compositions of wrought aluminium alloys. The comparison of the IGC test and the electrochemical fatigue test for alloy 2024 showed similar results for an immersion time period of 9000 s. The electrochemical test revealed that corrosion progresses up to 5400 s, then it stopped. The biggest step happened from 1800 to 3600 s when the IGC cracks extended up to 170 µm. On the other hand, the depth of the IGC in alloy 6082 is much shallower than in alloy 2024, especially the IGC generated with the IGC test according to PV1113. Comparing the data for the crack-penetration depth at 3600 s, the fatigue time for the 2024 alloy, and the 7200 s fatigue time for the 6082 alloy, a good correlation with the conventional PV 1113 standard method was obtained.

Electrochemical corrosion Intergranular corrosion Aluminium alloys Wrought Comparative testing

Introduction In aluminium alloys, particularly those that are heavily involved in the automotive and aerospace segments, improvements to the corrosion resistance, based on a fundamental understanding of the initiation and the propagation of the corrosion attack, are very important for their increased commercialization [1–5]. Although it has been well known for several decades that the stress corrosion cracking (SCC) of aluminium alloys is almost exclusively intergranular (IGC), the exact contribution of the alloy’s composition and the various processing parameters (the entire processing path) on the IGC resistance is still unclear. This gap in knowledge is particularly present in recently developed wrought aluminium alloys for demanding applications. In this work, for providing a better understanding of the role and the impact of various processing parameters, the results of an existing intergranular corrosion testing of selected wrought aluminium alloys (typically based on the metallographic investigation of the type, extent, and depth of intergranular corrosion), are combined and correlated with the findings of electrochemical studies performed in parallel on the same species. The presented results for the alloys 2024 and 6082 are part of a larger study of the corrosion resistance of various aluminium alloys as a function of the changes in the processing path as well as the influence of various corrosive environments on the corrosion behaviour.

V. Kevorkijan (&)
L. Skledar
M. Degiampietro
I. Lesjak
T. Krumpak Impol R in R d.o.o, Partizanska ulica 38, 2310 Slovenska Bistrica, Slovenia e-mail: [email protected] © The Minerals, Metals & Materials Society 2019 C. Chesonis (ed.), Light Metals 2019, The Minerals, Metals & Materials Series, https://doi.org/10.1007/978-3-030-05864-7_42

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Experimental Materials Corrosion susceptibility was tested for the alloy EN-AW2024 (referred to as the 2024 alloy) and extruded profiles based on an alloy EN-AW6082 (the 6082 alloy) produced in Impol by casting and extrusion, both were in the T1 condition (cooled from an elevated-temperature shaping process and naturally aged). Chemical composition of the applied alloys is reported in Tables 1 and 2.

The CP curves were measured after 72 h of immersion. The measurements started at −0.25 mV versus Eoc and continued with increasing potential in the anodic direction with a potential scan rate of m = 0.1 mV/s. The potential sweep was reversed in the cathodic direction when a current density of 1 mA was reached (however, due to the applied potential current density it increased slightly further). Repeat measurements were performed and a representative measurement was selected to report the CP results.

Intergranular Corrosion Test Electrochemical Testing and Techniques The working electrodes were embedded in a flat cell (provided by Gamry) and sealed with an o-ring to prevent leakage. The working electrode area exposed to the solution was 16.9 cm2. The experiments were performed in a three-electrode cell (volume 130 mL) closed to the air under stagnant conditions in the laboratory (23 ± 2 °C). A Ag/AgCl (saturated KCl) electrode was used as the reference, along with a graphite rod as a counter electrode. All the reported potentials refer to the Ag/AgCl scale. The measurements were carried out with an Autolab PGSTAT204 potentiostat/galvanostat controlled by the Nova 2.1 electrochemical program. The electrochemical measurements were conducted in sequence. From the start and in between the electrochemical impedance spectroscopy (EIS) measurements, chronopotentiometric measurements (E vs t) were carried out. Finally, cyclic polarization (CP) measurements were performed after 72 h of immersion. The EIS spectra were obtained in the frequency range from 100 kHz to 5 MHz with 10 points per decade and a 10-mV (peak-to-peak) amplitude for the excitation signal. The impedance spectra were collected at different immersion times (1, 3, 5, 7, 10, 15, 20, 24, 36, 48, 60 and 72 h) for the open-circuit potential, Eoc, to study the time-dependent behaviour of the different aluminium alloys.

IGC testing was performed according to the PV 1113 specification [5]. In accordance with PV1113 the samples were ground using 120—grit SiC paper (supplied by Struers), rinsed with acetone, and finally cleaned in an ultrasonic bath containing acetone. The samples were then immersed in a solution made from 1000 mL H2O, 20 g NaCl, and 100 mL HCl (25 wt%). The volume of the solution gave at least 8 mL per cm2 for the sample area. The test duration was 2 h. After the treatment all the samples were polished.

Intergranular Corrosion Investigation The intergranular corrosion was metallographically investigated. The depth of the intergranular corrosion was measured with an optical microscope at four locations for each sample.

Results and Discussion Electrochemical Measurements Chronopotentiometry Chronopotentiometric measurements were performed in the first 72 h of the alloy’s exposure to a 5 wt% NaCl solution in order to check for the steady-state conditions, which are

Table 1 Chemical composition of EN-AW2024 %Si

%Fe

%Cu

%Mn

%Mg

%Cr

Other

%Zn

%Ti

Other each

Others total

0.50

0.50

3.8–4.9

0.30–0.90

1.2–1.8

0.10

–

0.25

0.15

0.05

0.15

Table 2 Chemical composition of EN-AW6082 %Si

%Fe

%Cu

%Mn

%Mg

%Cr

Other

%Zn

%Ti

Other each

Others total

0.70–1.3

0.50

0.10

0.40–1.0

0.60–1.2

0.25

–

0.20

0.10

0.05

0.15

Comparative Electrochemical and Intergranular …

needed in order for the EIS measurements to be valid. The E versus t measurements for the 2024 and 6082 alloys are presented in Figs. 1 and 2, respectively. In both cases the potential is not changing significantly versus time, especially at the end of the chronopotentiometric experiment (the grey curve). Based on that we can conclude that the steady state for both alloys was obtained and we can consider the EIS measurement to be representative. The change in the colour of the chronopotentiometric curve represents the time when the EIS measurements were performed. As the potential before and after the EIS measurement did not change significantly, these measurements are considered as being non-destructive for the material.

333

EIS Measurements Figures 3 and 4 show the time-dependent EIS measurements for the 2024 and 6082 alloys, respectively. The detailed fitting procedure for these spectra is beyond the scope of this investigation. The EIS measurements will be employed here only for the evaluation of the polarisation resistance Rp. The Rp value can be evaluated in the Bode spectra (middle figure) as IZI  Rp at low frequencies. Rp is a measure of how the metallic material is resisting the release of its electron and transferring it to the electro-active species in solution. The higher the Rp value the more resistive is the metallic material. The latter can be connected with the general

Fig. 1 Chronopotentiometric measurement of 2024 alloy in 5 wt% NaCl solution

Fig. 2 Chronopotentiometric measurement of 6068 alloy in 5 wt% NaCl solution

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Fig. 3 EIS measurements for 2024 alloy in 5 wt% NaCl solution; Nyquist spectra (left), Bode modulus (middle), and Bode phase spectra (right)

Fig. 4 EIS measurements for 6082 alloy in 5 wt% NaCl solution; Nyquist spectra (left), Bode modulus (middle), and Bode phase spectra (right)

corrosion susceptibility. The higher the Rp the more the metallic material is resistant to general corrosion. The most representative measurement in terms of an aluminium alloy’s general corrosion susceptibility is the measurement after 72 h of immersion (dark-green spectrum in Figs. 3 and 4). The 2024 alloy has an Rp value of about 1000 X (Fig. 3), whereas the Rp value is higher in the case of the 6082 alloy, i.e., about 4000 X (Fig. 4). Based on the Rp values measured, a higher general corrosion resistance is expected for the 6082 alloy compared with the 2024 alloy in a 5 wt% NaCl solution. It should be pointed out that this test does not include any electrochemical fatigue and resembles the real corrosion situation when these materials are immersed in a 5 wt% NaCl solution.

in the forward scan has a shape that corresponds to the active behaviour, without a clearly developed Ebd (a rough estimation can, however, be made, as given in Fig. 5). On the other hand, the 6082 alloy has a more distinctively expressed Ebd. The shape of the curve for the latter can be explained with the active/passive type of behaviour, which additionally supports the higher general corrosion resistance compared

Cyclic Polarization Cyclic polarization (CP) measurements were performed at the end of the electrochemical tests, i.e., 72 h of immersion and the CP curves for the 2024 and 6082 are presented in Figs. 5 and 6, respectively. The arrows represent the scan direction (green arrows for the forward scan and black arrows for the reverse scan). The CP curve for the 2024 alloy

Fig. 5 CP curves for 2024 alloy measured after 72 h of immersion in 5 wt% NaCl solution

Comparative Electrochemical and Intergranular …

335

Fig. 6 CP curves for 6082 alloy measured after 72 h of immersion in 5 wt% NaCl solution

with the 2024 alloy (as found using EIS measurements). Moreover, passive behaviour with a partially developed Ebd could also explain the higher pitting corrosion resistance behaviour for the 6082 alloy compared with the 2024 alloy in 5 wt% NaCl. For both alloys, the switching potential was set at a value where the current reached 1 mA. Figures 5 and 6 show that both materials cannot repassivate after being electrochemically damaged as the current in the reverse direction is higher than in the forward direction. Localized corrosion is mainly due to the formation of pits and crevices. After the CP-curve measurements a metallographic investigation of the 2024 and 6082 alloys was performed. In both cases intergranular corrosion was not visible, even though localized corrosion was induced due to the polarization CP scan. Therefore, the above electrochemical tests are useful for studying general and localized corrosion susceptibility. To achieve intergranular corrosion the samples were electrochemically fatigued for a certain time period at a particular potential in order to force the intergranular corrosion to occur.

Fig. 7 Crack-penetration depth versus fatigue time for 2024 alloy in 5 wt% NaCl solution

Electrochemical Fatigue

Fig. 8 Crack-penetration depth versus fatigue time for 6082 alloy in 5 wt% NaCl solution

In order to electrochemically force the intergranular corrosion, a potential of 20 mV more positive than the breakdown potential, Ebd, was applied for different time periods, i.e., 1800, 3600, 5400, 7200, and 9000 s. For every test a new specimen was employed and a chronoamperometric measurement was carried out. After that test the specimens were metallographically investigated to determine the crackpenetration depth. Figures 7 and 8 show the change in the penetration depth versus the fatigue time for the 2024 and 6082 alloys, respectively. A quasi-linear (R2 = 0.96) increase in the penetration depth versus the fatigue time was found up to 3600 s in the

case of the 2024 alloy (Fig. 7). By increasing the fatigue time the crack-penetration depth does not change significantly up to 5400 s; however, it increases again at 7200 s. In the case of the 6082 alloy, the increase in the crack-penetration depth up to 7200 s is visible (Fig. 8). A better linear correlation is present (R2 = 0.99) compared with the 2024 alloy. By comparing the data for the crack-penetration depth at 3600 s, the fatigue time for the 2024 alloy, and the 7200 s fatigue time for the 6082 alloy, a good correlation with the conventional PV 1113 standard method was obtained (as described below).

336

Microstructure Evaluation of 2024 and 6082 Alloys An SEM (scanning electron microscope) investigation (Fig. 9) was performed to identify the main intermetallic phases and the micro-constituents with the purpose being to recognize the important corrosion paths. In the 2024 alloy, which is rich in copper, Al2Cu, Mg2Si and (Mn,Fe)3SiAl12 are present. The small particles in Fig. 9 are Al2Cu or Al2MgCu, which were precipitated from the a-Al super-saturated solid solution. The density of the precipitates in the microstructure of the 6082 alloy is significantly smaller than in the 2024 alloy. Some second phases are visible at the grain boundaries and are composed of Mg2Si. The intermetallic Mg2Si phases are large and stretched in the extrusion direction. The other main ingredient is an iron-based phase ((Mn,Fe)3SiAl12). The micro-constituents have a different corrosion potential than the a-Al super-saturated solid solution. In 2xxx alloys, the Al2Cu has a more negative corrosion potential that the base alloy’s material and represents the cathodic regions. In other alloys, such as Al-Mg-Fe-Si, precipitates like Mg2Si are anodic to the a-Al solid solution. Therefore, selective attack of the grain-boundary region can occur.

Material Structure in Correlation with IGC Progress The SEM investigation revealed the difference in the morphology of the IGC cracks, which also depend on the direction of the samples’ preparation. The IGC cracks are, in alloy 2024, deeper longitudinal in the direction of extrusion

a) 2024

V. Kevorkijan et al.

(Fig. 10a, b). In alloy 6082 the IGC depth is similar in both directions. Samples from alloy 2024 have a fibre structure, which is elongated in the direction of production. When the corrosion initiates, it can progress quickly and unhindered along the fibre grain boundary. This is the reason why the IGC cracks are much wider in the longitudinal direction, but also shallower. The alloy 2024 has thin fibres, so the morphology of the IGC crack is also thin. The density of the IM (intermetallic) particles on the fibre border is dense, which makes the 2024 alloy significantly more susceptible to corrosion. In the longitudinal direction, the IGC depth is smaller (Fig. 11). The samples from the alloy 6082 have a recrystallized layer with large grains on the outer skin of the profile. The grains represent an obstacle, which slows down the IGC process. The structure is similar in the longitudinal and transverse directions, so we also get a similar IGC depth in both directions.

Measurements of IGC The IGC penetration depth was measured using an optical microscope after the electrochemical and PV1113 testing. The IGC depth was measured at four locations for each sample, in the transverse and longitudinal directions. Tables 3 and 4 present only the maximum values of the intergranular corrosion for each sample. If we compare the IGC test and the electrochemical fatigue test for alloy 2024 we obtain similar results for an immersion time period of 9000 s. The electrochemical test reveals that the corrosion progresses up to 5400 s, then it stops. This is the nature of IGC, which is self-limiting when the supply of

b) 6082

Fig. 9 SEM microstructure images for a 2024 alloy and b 6082 alloy before corrosion tests

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a) 2024 /transverse/

b) 2024 / longitudinal/

c) 6082 / transverse /BEC 200x

d) 6082 / longitudinal/ BEC 200x

Fig. 10 SEM images of IGC in the 2024 and 6082 alloys

oxygen is depleted [3]. The progress of the IGC is not linear, and it depends on the location at which we took the measurements. The biggest step happened from 1800 to 3600 s when the IGC cracks extended up to 170 µm. The depth of the IGC in alloy 6082 is much shallower than in alloy 2024, especially the IGC generated with the IGC test according to PV1113. In the electrochemical testing the IGC progresses linearly to its final depth of 221 µm.

Conclusions This work describes the manner of aluminium alloy corrosion susceptibility testing that is ongoing at the company Impol. The alloys are tested in terms of general (using electrochemical impedance spectroscopy), localized (using cyclic polarization measurements) and intergranular corrosion (using the chronoamperometry technique) susceptibility using different electrochemical techniques and

metallographic approaches (e.g., the PV 1113 test). These procedures enable the selection of an appropriate alloy for a particular environment from the existing ones (that are produced by Impol). Moreover, this procedure offers the possibility to create even more corrosion-resistive alloys and enables the development of fundamental knowledge that explains the facts about what kind of metallurgical parameters are crucial for designing even more corrosion-resistant aluminium alloys than are currently available. The comparison of the IGC test and the electrochemical fatigue test for alloy 2024 showed similar results for an immersion time period of 9000 s. The electrochemical test revealed that corrosion progresses up to 5400 s, then it stopped. The biggest step happened from 1800 to 3600 s when the IGC cracks extended up to 170 µm. On the other hand, the depth of the IGC in alloy 6082 is much shallower than in alloy 2024, especially the IGC generated with the IGC test according to PV1113.

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a) 2024 /transverse/ 200x

b) 2024 / longitudinal/ 200x

c) 6082 / transverse /200x

d) 6082 / longitudinal/ 200x

Fig. 11 Structure of IGC crack progress Table 3 Maximum depth of IGC for alloy 2024

Alloy

Test

Time

Max. depth of IGC (µm)

2024

Electrochemical fatigue test

72 h

118

1800 s

152

3600 s

328

5400 s

367

7200 s

235

IGC test according to PV1113

9000 s

371

1–2 h

380

2–2 h

371

3–2 h

366

Comparative Electrochemical and Intergranular … Table 4 Maximum depth of IGC for alloy 6082

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Alloy

Test

Time

6082

Electrochemical fatigue test

0.5 h

IGC test according to PV1113

Comparing the data for the crack-penetration depth at 3600 s, the fatigue time for the 2024 alloy, and the 7200 s fatigue time for the 6082 alloy, a good correlation with the conventional PV 1113 standard method was obtained.

References 1. Gregor Žerjav, Matjaž Finšgar. Corrosion of aluminum and its alloys, Vakuumist 36 (2016)

Max. depth of IGC (µm) 53

72 h

22

3600 s

85

5400 s

178

7200 s

213

9000 s

221

1–2 h

19

2–2 h

53

3–2 h

31

4–2 h

33

2. N. Birbilis and G. Bucheit. Electrochemical Characteristic of Intermetallic Phases in Aluminum Alloys, Journal of The Electrochemical Society 152 (2004) 3. E. Ghali. Corrosion Resistance of Aluminum and Magnesium Alloys, Wiley Series in Corrosion, 218–224 (2010) 4. Anthony E. Hughes, Nick Birbili, Johannes M.C. Mol, Santiago J. Garcia, Xiaorong Zhou and George E. Thompson (2011). High Strength Al-Alloys: Microstructure, Corrosion and Principles of Protection (2011) 5. Volkswagen AG Koncernnorm PV 1113, 2007–10, Klass.— Nr.53312

Nature of Grain Boundary Precipitates and Stress Corrosion Cracking Behavior in Al 7075 and 7079 Alloys Ramasis Goswami

Abstract

Transmission electron microscopy (TEM) has been employed to investigate the nature and microchemistry of Grain boundary precipitates in Al 7079 and Al 7075 aged at the peak and over aged conditions to correlate with the stress corrosion cracking (SCC) behavior. The SCC plateau velocity in Al 7079 at T6 and T7 conditions is two to four orders of magnitude higher, respectively, as compared to Al 7075 T6 and T7. TEM studies revealed that the precipitates within grains in Al 7079 at the peak and overaged conditions is mostly T-phase (Al16Zn33Mg32), while the precipitate at grain boundaries is Al-Mg-Zn type quasicrystalline precipitate (Al15Mg44Zn41). The grain boundary phase in Al 7075 at peak and over aged conditions is hexagonal η phase with stoichiometry Mg(CuxZn1−x)2. We demonstrate that Al 7079 is more susceptible to SCC as compared to Al 7075 as a result of the formation of the quasicrystalline phase with relatively high Mg content at grain boundaries. Keywords











Microstructure Grain boundary precipitates Stress corrosion cracking Al alloys TEM

Introduction Aluminum 7000 series alloys have been extensively used for structural components in aircraft [1]. However, the stress corrosion cracking (SCC) in salt spray environments continues to be a problem [2, 3] as a result of the formation of grain boundary precipitates. Different aging treatments, such as (i) increasing grain-boundary precipitate size, spacing or volume fraction (ii) increasing precipitate free zone (PSZ) R. Goswami (&) Materials Science and Technology Division, Naval Research Laboratory, Washington, DC 20375, USA e-mail: [email protected]

width (iii) changes of microchemistry of grain boundary precipitates, and (iv) decreasing slip planarity have been employed to improve the SCC resistance of 7000 aluminum alloys. [4–8]. There are still unresolved questions about which factors are important in controlling the SCC behavior, partly because the various microstructural features are not independently controllable. In addition, the role of the local chemistry of aging, particularly the Cu content of the grain boundary precipitate, and the nature of grain boundary precipitate on the stress corrosion cracking behavior (SCC) of 7000 alloys is not known. Upon aging, considerable changes in the microstructure (precipitate size, spacing and precipitate free zone), and grain boundary precipitate composition has been reported. It has been shown that the SCC plateau velocity of Al-Zn-Mg-Cu alloys [9] decreases significantly with higher Cu content as a function of aging time. It has been shown that the increasing Cu content of the grain boundary precipitates with aging makes the precipitate more noble. Recent studies indicate that the quench rate from solution treatment temperature can also play a role in controlling the SCC behavior by affecting the microchemistry [10, 11]. The middle portion of the plate, which experienced slower quench rate showed higher SCC resistance. They reported that the changes in microstructural features, such as precipitate size, spacing, volume fraction and precipitate free zone, during over aging did not affect the SCC velocity in the near surface thickness (T/6) position of the 7079 alloy. They argued, based on the energy dispersive x-ray spectroscopy (EDS) and electrochemical open circuit potential (OCP) measurements that microchemistry, particularly the content of Cu of the grain boundary precipitate determined alloy susceptibility to SCC in salt water environment. Thus, it would be of interest to systematically investigate the effect of aging on the nature and microchemistry of grain boundary precipitates of 7075 Al and 7079 Al alloys to correlate with the SCC behavior. Here we examine the grain boundary microstructure at T6 and T7 conditions for Al 7075 and 7079, and correlate with the SCC behavior. We show that

© The Minerals, Metals & Materials Society 2019 C. Chesonis (ed.), Light Metals 2019, The Minerals, Metals & Materials Series, https://doi.org/10.1007/978-3-030-05864-7_43

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the nature and composition of precipitates at grain boundaries in 7079 and 7075 are very different, which can be linked to two to four orders of magnitude difference in SCC velocities between 7079 and 7075.

Experimental Details Thin plates (about 1 mm thick) of commercial 7000 series Al alloys at T6 and T7 conditions were obtained from Dr. Lynch of DSTO, Melbourne, Australia. For transmission electron microscopy (TEM), Philips CM-30 and JEOL 2200 analytical transmission electron microscopes operating at 300 and 200 keV, respectively, were used to characterize the microstructure of these alloys as a function of aging. TEM samples were prepared by initially polishing arc-cut disk samples mechanically and finally by thinning in an ion mill with a gun voltage of 5 kV, a current of 5 mA, and a sputtering angle of 10 at low temperatures. The fine probe energy dispersive X-ray spectroscopy (EDS) was employed to determine the distribution of Mg, Zn, Cu and Al at the grain boundaries, as well as within the matrix grains and precipitates. Further compositional information was obtained by high-angle annular dark field (HAADF) imaging with the scanning TEM (STEM) mode. Also known as Z-contrast imaging, with this imaging mode, the brighter regions correspond to heavier atoms, as the scattering cross-section is approximately proportional to the square of atomic number (Z).

Results and Discussion Figure 1 shows the SCC plateau velocity of 7079 Al remains constant for peak (T6) and over aged (T7) conditions for samples obtained from a thick plate [11]. The SCC plateau velocity is approximately 4  10−6 to 1  10−6 ms−1. On the other hand, the SCC plateau velocity for Al-7075 has been observed to decrease by around two orders of magnitude from approximately 10−8 to 10−10 ms−1 from peak aged to over aged condition. The SCC plateau velocity of Al 7075 is, thus, two and four orders of magnitude lower for the T6 and over aged sample, respectively, as compared to Al 7079. Here we have made attempts to correlate the SCC behavior with the nature and composition of grain boundary precipitates for two alloys at different aging conditions. The alloy compositions of Al 7075 and Al 7079 are given in Table 1. One could see that the Cu content, and the Zn to Mg ratio are considerably higher for 7075, as compared to 7079. The Zn/Mg ratio is 2.4 and 1.4 for 7075 and 7079,

Fig. 1 The SCC plateau velocity as a function of aging at 160 °C for samples obtained from T/6 locations of thick Al 7079 plates

respectively. The ternary phase diagram of Al-Zn-Mg at 120 °C, obtained using Thermocalc software, shows that the equilibrium phases in the composition range of 4–5 wt% Zn and 2–3.5 wt% Mg, are aAl and T-phase (Al16Mg32Zn33). Here we describe the nature and composition precipitate within grains and grain boundaries at T6 and T7 conditions for Al 7079 and Al 7075. Figure 2a is the TEM image of Al 7079 in the peak aged (T6) condition, showing the nanocrystalline precipitates within grains. The precipitates within a grain are mostly spherical dots with size ranging from 5 to 15 nm at T6 condition. These precipitates seem to grow considerably with a size range 10–20 nm at T7 condition (see Fig. 2b). In addition, these precipitates form on top of existing rod like dispersoids. Figure 3 is the high-resolution TEM (HRTEM) image close to [112] zone of Al in the peak aged (T6) condition, showing that the nanocrystalline (5 nm in size) T-phase (Al16Mg32Zn33) precipitates with approximately spherical morphology. The fast Fourier transform (FFT) obtained from one such particle and matrix is given as an inset. The FFT shows that 111Al and 220Al planes are parallel to 600T and 053T, respectively. In addition to nanocrystalline T phase, we could observe platelets of S-phase and a quasi-crystalline (QC) phase (see Fig. 4). The Al-Mg-Zn system exhibits complex intermetallic phases [12–15], such as s1 and s2 (Al15Mg43Zn42), quasicrystalline phase (Al15Mg44Zn41) and / phases with stoichiometry in the range of Al18Mg55Zn26 to Al28Mg55Zn17. Figure 4c, d show the presence of a nanocrystalline QC phase within a grain. The FFT obtained

Nature of Grain Boundary Precipitates and Stress … Table 1 Alloy compositions (wt %) for Al 7075 and Al 7079

Fig. 2 a, b TEM images showing the eta precipitates within Al grains in peak (T6) and over aged (T7) condition, respectively

Fig. 3 HRTEM image showing nanocrystalline T-phase particles within a grain. The FFT from one of the T-phase particles is shown as an inset

343

Zn

Mg

Cu

Fe

Si

Cr

Mn

Ti

Al

Al 7075

5.1

2.1

1.2

0.5

0.4

0.18

0.3

0.2

Balance

Al 7079

4.4

3.36

0.62

0.22

0.12

0.16

0.19

0.05

Balance

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R. Goswami

Fig. 4 a HRTEM image showing S platelet within the grain of Al 7079. b The corresponding FFT from the particle and the matrix. c HRTEM image showing a quasicrystalline particle. d The corresponding FFT, showing the 5-fold symmetry

from the HRTEM image (Fig. 4d) shows the 5-fold symmetry. In Al 7075 at T6 and T7 conditions, however, we mostly observe platelets of η, MgZn2, phase [16]. As the SCC in 7079 and 7075 is intergranular in nature [10, 11], we focus here on the microstructural features, such as the structure and composition of the precipitates at grain boundaries. These microstructural features at the grain boundaries control the electrochemical reaction at the crack tip and crack growth rate. Figure 5a–d shows the precipitation at a grain boundary of Al 7079 at the peak aged condition. The HRTEM image (see Fig. 5c) and the corresponding FFT show the precipitates are quasi-crystalline type. Similar QC type phase has been observed within grain in this condition (see Fig. 4d). For composition analysis, we perform fine probe (probe size 1 nm) EDS in HAADF imaging mode. Figures 6 and 7 show the precipitates at grain boundaries of Al 7079 at T6 and T7 conditions, respectively. In this mode, the most precipitates appear bright, suggesting that the precipitates contain more Cu and/or Zn as compared to the matrix. At both aging conditions, a bi-modal distribution of precipitates at grain boundaries was observed. A high density of fine precipitates at grain boundaries (size  50 nm) was

observed containing negligible amount of Cu (see Fig. 6a– d). The fine precipitates are QC type with stoichiometry Al15Mg44Zn41. The EDS measurements from the fine QC precipitates show higher Mg content with the average ratio of Mg to Zn of 1.3. In addition, the grain boundaries have larger (size  200 nm) precipitates (see Fig. 6a, b) with higher Cu content (10 at.%), which are mostly Mg(CuxZn1 −x)2. The composition maps of Mg, Al, Cu and Zn at peak aged conditions were shown in Fig. 6e–h. Lines scans of Mg, Cu and Zn were extracted from the maps, showing the relative proportions of the element at grain boundary precipitate. A similar trend was observed in the over aged, T7, condition for Al 7079 sample. The coarse grain boundary precipitate (size  200 nm) is shown in Fig. 7a–f, containing 13 at.% of Cu, while the fine precipitates show relatively higher Mg and small amount of Cu at over aged condition (see Fig. 7g–l). In addition, the HRTEM studies show that the fine precipitates at grain boundaries at over aged condition, T7, are quasicrystalline. On the other hand, in Al 7075, TEM studies showed that the grain boundary precipitates are η phase [17], (Mg(CuxZn1−x)2), with considerable amount of Cu in it (see Fig. 8). HRTEM analysis of precipitates at grain

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345

Fig. 5 High angle annular dark field (HAADF) image showing the coarse and fine precipitates at grain boundary at peak aged condition. The composition maps, and line scans of Mg, Cu and Zn from coarse and fine particles were shown

boundaries and the fine probe EDS showed that the grain boundary precipitates at peak and over aged conditions are mostly hexagonal η phase with stoichiometry Mg(CuxZn1 −x)2. In addition, TEM studies revealed that in the over aged condition the Cu content of the η phase increases at grain boundaries. The HAADF image at the peak condition and the corresponding composition maps of Mg, Al, Cu and Zn were shown (Fig. 9a, e). The line scan of Mg, Cu and Zn was extracted from the map, showing the relative proportions of the element at grain boundary precipitate. The overall composition of precipitate as a function of aging for naturally aged, T6 and T7 conditions is given in Fig. 9g. While a significant increase in Cu content as a function of aging was observed, the amount of Zn decreases considerably with aging. The Mg increases considerably at peak aged condition as compared to naturally aged (NA) condition. At peak age condition, the average content of Mg, Cu and Zn is

45.18, 15.08, 39.73 at.%, respectively. The average Mg, Cu, Zn at over aged condition is 40.0, 20.00 and 40.00 at.%, respectively. The SCC studies (see Fig. 1) of this alloy showed that the plateau velocity of 7079 Al remains constant for peak (T6) and over aged (T7) conditions. On the other hand, the SCC plateau velocity of Al 7075 in T6 and T7 is two to four orders of magnitude lower as compared to T6 and T7, respectively, of Al 7079. This behavior can be correlated with the nature (structure and composition) of grain boundary precipitates in both alloys. In Al 7079, two types of grain boundary precipitates are observed. The fine precipitates are mostly quasi-crystalline, containing higher amount Mg (see Fig. 6d), while the coarse precipitates are η phase, Mg(CuxZn1−x)2, containing considerable amount of Cu. The QC type precipitates at grain boundaries are more electrochemically active as a result of higher Mg content as

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Fig. 6 High angle annular dark field (HAADF) image showing the coarse and fine eta precipitates at grain boundary at over aged condition. The composition maps, and line scans of Mg, Cu and Zn from coarse and fine particles were shown

compared to the η phase. In Al 7075, the η phase at T6 and T7 conditions has relatively high amount of Cu (see Figs. 8 and 9), which makes the precipitates less active electrochemically as compared to the QC phase. This suggests that the higher dissolution rate of quasi-crystalline (Al15Mg44Zn41) precipitates at grain boundaries in Al 7079, as compared to the Mg(CuxZn1−x)2 in Al 7075, is responsible for the higher SCC plateau velocity in Al 7079. These experimental findings suggest that the nature (structure and stoichiometry) of grain boundary precipitate, rather than the grain boundary precipitate size and spacing, is critically important for controlling the SCC behavior in Al 7xxx series alloys.

Summary and Conclusions TEM was employed to investigate the microchemistry and microstructure of grain boundary precipitates in Al 7079 and Al 7075 aged at room T6 and T7 conditions to correlate with the SCC behavior. We have observed that the SCC plateau velocity in Al 7079 at T6 and T7 conditions is two to four orders of magnitude higher, respectively, as compared to Al 7075. A high density of quasicrystalline phase (Al15Mg44Zn41) precipitates was observed at grain boundaries at the peak and over aged conditions. The fine probe EDS results with a probe size of 1 nm showed that the

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Fig. 7 a–c TEM showing the precipitation at a grain boundary in Al-7079 at T6 condition. d The FFT obtained from the HRTEM image showing the 5-fold symmetry

Fig. 8 a A bright-field TEM image at peak aged condition showing a grain boundary with several precipitates in Al 7075. b A HRTEM image of one such precipitate showing the crystal structure of the precipitate conforms to hexagonal MgZn2

amount of Cu in the grain boundary precipitates in Al 7079 is small. On the other hand, in Al 7075 a different type of precipitate at grain boundaries was observed. TEM studies of

precipitates at grain boundaries in Al 7075 show that the precipitate is the η phase with stoichiometry Mg(CuxZn1−x)2. The average Cu content in Al 7075 increases from 15 and

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Fig. 9 a A HAADF image containing grain boundary precipitate for peak aged sample. b–e The elemental maps of Mg, Al, Cu and Zn. f A line scan across the grain boundary from the region marked by a thick

arrow in “a”. g The average composition of Zn, Mg and Cu of the grain boundary precipitate as a function of aging condition, NA (naturally aged), T6 (peak aged) and T7 (over aged)

20 at.% with aging from the peak to over aged conditions, which decreases the plateau velocity further in over aged condition. We demonstrate that the nature (structure) and composition of precipitates at grain boundaries in 7079 and 7075 are very different, and show that Al 7079 becomes more susceptible to SCC, as compared to Al 7075, as a result of the formation of the quasicrystalline precipitates with stoichiometry Al15Mg44Zn41 at grain boundaries.

5. S.P. Lynch, S.P. Knight, N. Birbilis and B.C. Muddle, in Effects of Hydrogen on Materials, Eds. B. Somerday, P. Sofronis and R. Jones, ASM International, Metals Park, OH, 2009, pp. 243–250. 6. N.J.H. Holroyd, “Environment-induced cracking of high-strength aluminum alloys” in Proceedings of Environment-induced cracking of metals, 1988 (Eds.: R. P. Gangloff, M. B. Ives), NACE, Houston, (1990), pp. 311–345. 7. A.K. Vasudevan and K. Sadananda, Metal. Mater. Trans. A, 2011, vol. 42A, 405–414. 8. P.K. Poulose, J.R. Morral, A.J. McEvily, Metall. Trans., 1974, Vol. 5, pp. 1393–1400. 9. B. Sarkar, M. Marek and E.A. Starke, Metal. Trans., A, 1981, vol. 12A, pp. 1939–1943. 10. S.P. Knight, Ph.D thesis, “Stress Corrosion Cracking of Al-Zn-Mg-Cu Alloys Effects of Heat-Treatment, Environment and Alloy Composition” 2008, Monash University, Australia. 11. P. Knight, K. Pohl, N.J.H. Holroyd, N. Birbilis, P.A. Rometsch, B. C. Muddle, R. Goswami, S.P. Lynch, Corrosion Science, 2015, 98, 50–62 (2015). 12. G. Bergman, J. L. T. Waugh, and L. Pauling, Acta Crystallogr. 10 (1957) 254. 13. K. Edagawa, N. Naito, and S. Takeuchi, Phil. Mag. B 65 (1992) 1011. 14. T. Takeuchi et al., J. Non-Cryst. Solids 156–158 (1993) 914. 15. T. Takeuchi, and U. Mizutani, Phys. Rev. B. 52 (1995) 9300. 16. L. Bourgeois, B. C. Muddle, and J. F. Nie, Acta Mater. 49 (2001) 2701. 17. R. Goswami, S. Lynch, N.J.H. Holroyd, S.P. Knight and R.L. Holtz, Metal. Trans. A, 44, 1268 (2013).

Acknowledgements The author gratefully acknowledges the Office of Naval Research through NRL’s 6.1 base program. The author also thanks S. Lynch and S.P. Knight for the SCC data, and for supplying Al-7079 alloy for microstructural analysis.

References 1. J.P. Immarigeon, R.T. Holtz, A.K. Koul, L. Zhao, W. Wallace and J.C. Beddoes, Materials Characterization, 1995, vol. 35, 41–67. 2. S. Russo, P.K. Sharp, R. Dhamari, T.B. Mills, B.R.W. Hinton, G. Clark, and K. Shankar, Fat. Fract. Engg. Mater. Struct., 2009, vol. 32, 464–472. 3. M.O. Speidel, Metallurgical Transactions A, 1975, vol .6A, pp. 631–651. 4. S.P. Knight, N. Birbilis, B.C. Muddle, A.R. Trueman, and S. P. Lynch, Corrosion Science, 2010, vol. 52, 4073–4080.

Part VII Aluminum Alloys, Processing and Characterization: Characterizations and Applications of Aluminum Alloys

Effect of Homogenization on Al-Fe-Si Centerline Segregation of Twin-Roll Cast Aluminum Alloy AA 8011 Sooraj Patel and Jyoti Mukhopadhyay

Abstract

The effect of homogenization on centerline segregation has been studied in twin roll cast aluminum alloy AA 8011. It is observed that second phase particles generally form when the alloy contains high Fe and Si. During twin-roll casting process, beta phase of AlFeSi segregates at the centre of the strip in the thickness range of 10–15 µm. Such phase has a needle shape morphology that inversely affects the formability. Phase transformation from b-AlFeSi to a-AlFeSi is found to occur when homogenization is carried out at high temperature. During the phase transformation, the morphology of second phase particles also changes from needle to circular shape. Furthermore, it is also observed that the area fraction of second phase particles decreases with an increase in time and temperature. If homogenization temperature is increased, particle size growth is found to be dominant on the spread of intermetallic particles. Keywords







Twin-roll cast Centerline segregation tion Morphology




Homogeniza-

Introduction Aluminium is the second most commonly used material after Iron. A thin aluminum strip can be produced by two different processes: (i) Direct chill casting (ii) Continuous casting/ Twin roll casting. Bessember [1] gave an idea of twin roll casting while using two harden rolls and the small crucible of 9 kg capacity. Continuous strip casting for aluminum and its alloys was carried out by J. Hunter and W. Lauener in 1950 [2]. In twin roll casting process, molten metal was S. Patel
J. Mukhopadhyay (&) Department of Materials Science & Engineering, Indian Institute of Technology, Gandhinagar, 382355, India e-mail: [email protected]

directly converted into 6–7 mm thick strip. Annealing and cold rolling operations were performed on this 6–7 mm thick strip to get the required thickness as well as mechanical properties [3, 4]. In Twin roll casting, centre-line segregation of second phase particles was most commonly found for high alloying content materials [5–11]. Ghosh [5] highlighted that physical movement of liquid and solid phases resulted into the macrosegregation due to the localization of microsegregation. Such second phase particles can move inward easily through the columnar zone. These particles agglomerate at the centre region of the strip cast alloy. If the foil undergoes further rolling, these particles come out from the matrix and create pin-holes. It occurs due to the mismatch in the mechanical properties of intermetallic particles with the base matrix [6]. The formation of pinholes must be prevented to reduce the moisture vapour and oxygen transmission rate as well as ultraviolet ray to produce an excellent quality of foil. Therefore, it is necessary to reduce centre-line segregation in order to enhance the downstream applications of foil for packaging materials. In the present work, centre-line segregation of Al-Fe-Si compound is observed in high Fe and Si content 7 mm twin roll cast aluminum alloy AA 8011. Needle type morphology that inversely affects the formability is identified as the beta phase of AlFeSi compound. The second phase particles are also confirmed using Fe:Si ratio. Strip cast AA 8011 was homogenized at different temperatures and phase transformation from b-AlFeSi to a-AlFeSi was also evaluated. The objective of present communication is two folds as given below. (i) To identify the phase transformation of AlFeSi compound concerning the morphology of the phases. (ii) To determine the effect of homogenization on centerline segregation by considering the mean aspect ratio, mean intermetallic spacing and area fraction.

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Experimental Procedure High Fe and Si content strip cast aluminum alloy AA 8011 was used in the investigation. Strip cast aluminum alloy AA 8011 with 7 mm thickness was procured from Jawaharlal Nehru Aluminum Research Development and Design Centre (JNARDDC), Nagpur. The chemical composition of AA 8011 collected for characterization study is shown in Table 1. Before pouring the molten metal in between the rollers, holding furnace temperature and headbox temperatures were kept at 800 °C and 700 ± 5 °C respectively. The feed rate of molten metal that passed was kept 0.9 m/min. Second phase particles inside the centre-line segregation were characterized using JEOL (JSM 7600F) Scanning Electron Microscope at IIT Gandhinagar. Elemental analysis was carried out using EDS attachment (Oxford, Model INCA Energy 250 EDS). The phases of second phase particles were identified using Fe to Si ratio. Homogenization was carried out using Nabertherm high-temperature furnace. Specimens were homogenized at 525, 550, 575 and 600 °C for 12 h respectively. The phase change from b-AlFeSi to a-AlFeSi was found to occur after 550 °C. The phase diagram for the equilibrium is shown in Fig. 1. Accordingly, homogenization was performed at different temperatures Table 1 Chemical composition of AA 8011 (wt%)

Fig. 1 Al-Fe-Si ternary phase diagram (for Fe = 0.62 wt%) [FactSage]

from 525 to 600 °C for different times (4, 8 and 24 h) respectively. Homogenization condition for all the specimens is shown in Fig. 2. Specimens were heated to a particular temperature in 2.5 h. The heating rate was kept slow to ensure the thermal equilibrium between the sample and furnace. Specimens were cooled inside the furnace from homogenization temperature to the room temperature. The cooling rate was assumed to be constant since it was not considered for further study. All the specimens were prepared for SEM analysis after homogenization. Elemental analysis was performed for the specimens. The second phase particles were analyzed by performing critical analysis, such as aspect ratio, the area fraction of the intermetallic compound, the mean distance between two intermetallic compounds.

Results and Discussion Centerline segregation can be identified using optical microscopy. Scanning Electron Microscopy (SEM) was carried out to characterize the second phase particles that were difficult to observe using optical microscopy. Such particles were found to be segregated at the centre in the

Alloy

Si

Fe

Cu

Mn

Mg

Ti

Al

AA 8011

0.6

0.62

0.01

0.004

0.001

0.009

98.74

Effect of Homogenization on Al-Fe-Si Centerline …

Fig. 2 Homogenization of strip cast AA 8011

range of 10–15 µm thickness in 7 mm thick strip. Second phase particles having sharp needle type morphology were found in centerline segregation as shown in Fig. 3. These particles were also much closure to each other. Elemental analysis was performed on one of the needle type intermetallic compounds as shown in Fig. 4. It was found that the Fe:Si ratio (wt%) was nearly 2:1. The atomic ratio of Fe:Si was quite close to unity. The chemical composition of Al5FeSi /Al9Fe2Si2 was reported for b Al-Fe-Si phase [3, 8, 12]. Therefore, b-AlFeSi phase was confirmed based on Fe: Si ratio and with the morphology of second phase particles. The second phase particles inside the centerline segregation after different homogenization conditions are shown in Fig. 5. Few particles were converted into an irregular shape and remaining all particles were still found in needle type morphology after homogenization at 550 °C. Second phase particles were found to be converted into circular shape after homogenization at 575 °C. Chemical composition was identified for different morphology. Fe:Si ratio was found to vary concerning morphology as shown in Table 2. Elemental analysis was performed for both needle type and irregular shape particles after homogenization at 550 °C for 12 h. Fe:Si ratio for the needle type intermetallic compound Fig. 4 Elemental analysis of needle type second phase particle

353

Fig. 3 Centerline segregation in strip cast AA 8011

was nearly 2:1 and this was quite close to unity in wt% and atomic% respectively. Therefore, b phase could be confirmed for the needle type particles. The ratio for the irregular intermetallic compound was measured nearly 4:1 and 2:1 in wt% and atomic% respectively. Similar Fe:Si ratio was also found for a phase of Al-Fe-Si as it formed Al8Fe2Si/Al12Fe3Si2 intermetallic compound [12]. Therefore, a-AlFeSi could be confirmed for the irregular shaped second phase particle. However, such phase transformation was observed for very few particles. The similar ratio was also observed for the circular particles after homogenization at 575 °C. Therefore, the phase transformation from b-AlFeSi to a-AlFeSi was confirmed based on morphology and Fe:Si ratio. Aspect ratio, the mean intermetallic spacing and area fraction of second phase particles are also shown in Table 2. Phase transformation highly depends on temperature as compared to time. The mean aspect ratio, intermetallic spacing and area fraction of second phase particles for each homogenization condition are shown in Fig. 6a–c respectively. It can be concluded that a significant phase transformation has taken place at 575 °C. The maximum difference

Element

Wt %

Atomic%

Al

85.90

90.41

Si

4.83

4.88

Fe

9.27

4.71

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Fig. 5 Second phase particles inside centerline segregation after homogenization at 525 °C for 12 h (a), 550 °C for 4 h (b), 550 °C for 8 h (c), 550 °C for 12 h (d), 550 °C for 24 h (e), 575 °C for 4 h (f), 575 °C for 8 h (g), 575 °C for 12 h (h), 575 °C for 24 h (i) and 600 °C for 12 h (j)

Table 2 Effect of different homogenization condition on centerline segregation

Sr.

Homogenization condition

Morphology of second phase particle

Fe:Si ratio wt %

Atomic %

Mean aspect ratio

Mean intermetallic spacing (µm)

Area fraction (%)

1

As received

Needle

1.92

0.97

15.12

0.36

32.48

2

525 °C for 12 h

Needle

1.98

0.99

6.184

1.24

20.57

3

550 °C for 8 h

Needle

1.77

0.89

3.82

1.21

19.54

4

550 °C for 12 h

Needle

1.95

0.98

3.13

1.45

18.77

Irregular

4.13

2.08

5

550 °C for 24 h

Needle

1.83

0.92

3.47

1.79

16.59

6

575 °C for 4 h

Circular

3.45

1.73

2.43

2.73

19.33

7

575 °C for 8 h

Circular

3.57

1.8

1.68

2.15

17.82

8

575 °C for 12 h

Circular

3.33

1.67

1.57

2.72

15.7

9

575 °C for 24 h

Circular

3.57

1.8

1.37

2.87

12.4

10

600 °C for 12 h

Circular

3.2

1.61

*1

3.58

13.7

in aspect ratio was found to occur in between 4 and 8 h homogenization period but the same was not observed after 8 h. Therefore, homogenization at 575 °C for 8 h could be considered as the optimum homogenization parameter for the twin roll casting. The second phase particles spread at higher

temperature and these increase with an increase in time. Therefore, the mean intermetallic spacing was also increased concerning both time and temperature. The intermetallic compounds per unit area were reduced due to the dispersion of intermetallic particles. Therefore, area fraction was

Effect of Homogenization on Al-Fe-Si Centerline …

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Fig. 6 Aspect ratio (a), mean intermetallic spacing (b) and area fraction (c) of second phase particles for each homogenization condition

decreased with increase in time. As the homogenization was switched to a higher temperature, the growth in size of intermetallic particles was found to be more dominant than the spread. Therefore, though the mean intermetallic spacing was increasing, more area fraction was observed for homogenization at 575 °C for 4 and 8 h specimen as compared to homogenization at 550 °C for 24 h.

Conclusion 1. Second phase particles of Al-Fe-Si compound agglomerate inside the centerline segregation. Needle type second phase particles are in beta phase whereas circular particles are in alpha phase. Phase transformation highly depends on temperature as compared to time. Significant phase transformation from b-AlFeSi to a-AlFeSi is observed when homogenized at 575 °C. Accordingly, the morphology of intermetallic particles also changes from needle to circular shape. 2. The spread of intermetallic particles along with particles size growth takes place at high-temperature homogenization. The area fraction of second phase particles reduces with increase in time. However, if the homogenization is switched to high temperature, it is observed that the growth in particle size is more dominant than the spread.

Acknowledgements Authors wish to acknowledge Mr. RN Chouhan and JNARDDC Nagpur for providing Twin roll cast AA 8011. Authors also wish to acknowledge Mr. Amit Singh (IIT Gandhinagar) and SAIF, IIT Bombay for performing SEM experiment. The support of IIT Gandhinagar is highly acknowledged.

References 1. H. Bessember; Improvement in the Manufacture of Iron and Steel; US patent: 49053. July 25, 1865 2. R. Cook, P.G. Growcock, P.M. Thomas, D.V. Edmonds, J.D. Hunt (1995); Development of Twin Roll Casting Process; Journal of Materials Processing Technology 55, 76–84 3. Martin Lentz, Galyna Laptyeva, Olaf Engler (2016); Characterization of second-phase particles in two aluminium foil alloys; Journal of Alloys and Compounds 660, 276–288 4. Yücel Birol (2008); Response to annealing treatments of twin-roll cast thin Al–Fe–Si strips; Journal of Alloys and Compounds 458, 265–270 5. A Ghosh (February–April 2001); Segregation in Cast Products; Sadhana, Vol. 26, Parts 1 & 2, pp. 5–24 6. Ozgul Keles, Murat Dundar (2007); Aluminum foil: Its typical quality problems and their causes; Journal of Materials Processing Technology 186, pp. 125–137 7. Ch. Gras, M. Meredith, J.D. Hunt (2005); Micro-defects formation during the twin-roll casting of Al–Mg–Mn aluminum alloys; Journal of Materials Processing Technology 167, pp. 62–72 8. Ranjeet Kumar, Aman Gupta, Amit Kumar, R.N. Chouhan, Rajesh K. Khatirkar (2018); Microstructure and texture development during deformation and recrystallization in strip cast AA8011 aluminum alloy; Journal of Alloys and Compounds 742, pp. 369– 382 9. H. westengen (1984); Twin-roll casting of aluminum: The occurrence of structure in homogeneity and defects in as cast strip; Light Metals 1984, J.P. McGee, Editor pp. 972–980 10. R. E. Sanders Jr., P. A. Hollinshead, E. A. Simielli (2004); Industrial Development of Non-Heat Treatable Aluminum Alloys; 9th International Conference on Aluminium Alloys, Institute of Materials Engineering Australasia Ltd pp. 53–64 11. Aziz Dursun, Beril Çorlu, Canan İnel, S. Levent Aktuğ, Murat Dündar; Effect of Homogenization Treatment on Microstructural Evolution of 1050 and 1200 TRC Aluminum Alloys; Assan Aluminum, Tuzla, Istanbul, 34940 Turkey 12. C.M. Allen, K.A.Q. O’Reilly, B. Cantor, P.V. Evans (1998); Intermetallic phase selection in 1XXX Al alloys; Progress in Materials Science 43, pp. 89–170

Effect of Mg and Si Content in Aluminum Alloys on Friction Surfacing Processing Behavior Jonas Ehrich, Arne Roos, and Stefanie Hanke

Abstract

Friction surfacing (FS) coating layers are generated through severe plastic deformation (SPD) at elevated temperatures (
0.8 Tmelt). Alloying elements in metals affect heat generation and dynamic recrystallization kinetics during SPD, and therefore require significant adjustments of FS processing conditions. In this study, custom made Aluminum alloys (AA 6060 with additions of 2 and 3.5 wt% Mg, and 6.6, 10.4 and 14.6 wt% Si) were processed by FS. It was found that for the high-Mg Aluminum alloys especially the rotational speeds require a downward adaption to achieve a steady state process. A higher content of Mg results in a reduced rate of thermal softening and more efficient heat generation. With regard to the plasticization behavior during FS, the high amount of hard phases in the high-Si alloys was expected to cause additional friction and increase heat generation. However, as the Si content increases, the process temperatures decrease. Influences of Mg and Si content on material efficiency and coating dimensions were evaluated and discussed. Keywords





Friction surfacing Aluminum Silicon Solid state joining



Magnesium



Introduction Friction Surfacing (FS) has the particular potential to adjust mechanical properties of components locally, by increasing the material thickness. The joining technology FS is J. Ehrich (&)  S. Hanke Materials Science and Engineering, University of Duisburg-Essen, Duisburg, Germany e-mail: [email protected] A. Roos Institute of Materials Research, Helmholtz-Zentrum Geesthacht GmbH, Geesthacht, Germany

generally used to deposit coatings made of metals in solid state, i.e. without being melted. During FS a rotating consumable stud is pressed normally with a defined pressure upon the substrate. Due to the high friction in the contact zone, the material is heated and eventually plasticizes. The generation of heat is only introduced by mechanical energy caused through friction dissipation in the interfaces and internal plastic material flow of the stud. These thermomechanical occurrences lead to a recrystallized microstructure. It has been shown for different materials that dynamic recrystallization (DRX) takes place during FS [1]. Conventional FS takes place in three consecutive processing steps. First, the clamped stud experiences rotational movement, and either in force control or velocity control mode it is pressed upon the substrate. Since heat is supplied by the high friction between the stud’s tip and the substrate, the material begins to plasticize and turns into a viscoplastic state. At the same time, such softened material is squeezed out from the contact area and builds up a flash around the revolving stud. This leads to shortening of the stud, and after reaching a predefined value of shortening, 0.5–1 mm in this study, a translational speed is superimposed. A few seconds later a steady state is reached, in which the reaction forces, moments and heat generation can be assumed as constant. A running FS process is illustrated in Fig. 1. When the end constraint (e.g. maximum stud-shortening or lateral position) is reached, the process is terminated in the following sequence: translational speed is stopped, stud moves upwards out of contact and the rotational speed is stopped. The most deciding factors of FS processing behavior are the rotational speed n, axial force Fz and translational speed vx. The typical influences of those process parameters on the coating development have been widely investigated. It has been reported, a.o., for stainless steel [2, 3] and for Aluminium alloy 5052 [4] that with higher axial force and rotational speed the coatings’ thickness and width decrease. For Ti-6Al-4V on the other hand, within a range of rotational speeds from 300 to 6000 min−1, an initial increase followed by a decrease in deposited coating volume was observed [5].

© The Minerals, Metals & Materials Society 2019 C. Chesonis (ed.), Light Metals 2019, The Minerals, Metals & Materials Series, https://doi.org/10.1007/978-3-030-05864-7_45

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only in their content either in Mg or Si, were processed by FS. Differences in process characteristics and layer geometry when applying the same process parameters to all alloys, as well as the effects of changing parameters are observed. The results from this systematic approach allow to formulate recommendations for the FS process development for other aluminum alloys, and provide a basis for further research on metallurgical fundamentals.

Experimental

Fig. 1 Running FS process

The efficiency of the process, i.e. the fraction of the stud actually deposited, changes with the rotational speed of the stud. The efficiency (deposited material yield) decreases typically as thickness and width of the deposited layer decrease, too [2, 4]. When applying the FS process to a new alloy, no theoretical approach, e.g. based on material properties or alloying elements, to predict suitable process parameters is available. The process is then developed by starting with parameters reported for a similar material, and improving the results by trial and error. This fact shows that the fundamental mechanisms determining the heat generation, thermal softening and material flow behavior during FS are not understood to date [6]. In order to gain a more fundamental understanding of the effects of alloying elements on the processing behavior, in the current study custom made aluminum alloys, differing

Aluminum alloys were custom made by remelting the precipitation hardenable alloy AA 6060 from one single production batch, and adding either Mg or Si to different amounts. The modified alloys, as well as a sample of the original AA 6060, were cast into small, slightly conical dies, resulting in as-cast rods of approximately 110 mm length and 25 mm diameter, from each of which a stud for FS could be machined. All cast rods underwent a homogenization heat treatment, for 72 h at 535 °C, in order to adjust a uniformly distributed microstructure in all materials. For comparison, wrought studs from the same AA 6060 batch in T6 state were also used in this study. The chemical compositions of the stud materials used in this study are given in Table 1. The consumable studs were machined to dimensions of 20 mm in diameter and 80–90 mm of length. Sheets made of the precipitation-hardenable Aluminum alloy AA 2024 solution heat-treated, stress-relieved by controlled stretching and naturally aged to T351 state were used as the substrate material with dimensions of 300  130  8 mm. FS using cast Aluminum with particular compositions (high Si and Mg content) has not been published yet. Hence, for all tailor-made alloys, stable FS process windows were elaborated using a custom-designed machine. This machine serves only for research and investigations in solid state joining procedures. With its high range of capacity (axial force up to 60 kN, maximum spindle torque 200 Nm, 6000 min−1) dedicated studies have been performed, a.o. on Ti-based [5],

Table 1 Chemical composition of custom made Aluminum alloys Element (weight%) Alloy

Al

Si

Fe

Cu

Mn

Mg

Cr

Zn

Ti

AA 6060 wrought

bal

0.38

0.183

0.015

0.0091

0.299

0.0017

0.022

0.018

AA 6060 cast

bal

0.366

0.172

0.013

0.0092

0.273

0.0015

0.0078

0.018

AA 6060 + 2% Mg

bal

0.383

0.186

0.012

0.009

1.940

0.003

0.003

0.016

AA 6060 + 3.5% Mg

bal

0.388

0.192

0.014

0.009

3.480

0.003

0.007

0.015

AA 6060 + 6.6% Si

bal

6.610

0.198

0.016

0.009

0.253

0.002

0.003

0.017

AA 6060 + 10.4% Si

bal

10.370

0.201

0.011

0.009

0.245

0.002

0.003

0.014

AA 6060 + 14.6% Si

bal

14.600

0.227

0.011

0.010

0.232

0.002

0.001

0.013

Effect of Mg and Si Content in Aluminum Alloys …

359

Ni-based [7] and Al-based layers [6, 8]. It can be operated either in force control mode or in stud consumption rate control mode. The relative position of stud and substrate, the spindle torque and forces in three directions are recorded during the processing and evaluated. In this study, firstly depositions of all custom-made alloys were generated using a single set of process parameters, resulting in different layer geometries. Subsequently, depositions were produced by means of varying parameters, adjusted as to achieve similar layer geometries for all alloys. The investigations of the process and layer properties were carried out focusing on steady state material flow. In addition to evaluating the above mentioned, directly recorded process characteristics, the efficiency η of the deposited material volume versus the consumed stud volume was calculated according to the formula: g¼

Vdeposited d  w  vx  100% ¼  100% Vconsumed p  r 2  vCR

ð1Þ

with vCR ¼

DsZ Dt

ð2Þ

where d is the layer thickness, w is layer width, vCR is the stud consumption rate, r is the stud radius (10 mm), DsZ is the consumed stud length and Dt is the time difference. Furthermore, a mathematical approach was used to calculate the induced mechanical power P and the specific energy input per unit volume es: P ¼ PT þ Px þ Pz ¼ ð2  p  n  T Þ þ ðFx  vx Þ þ ðFz  vCR Þ ð3Þ PT þ Pz p  rC  vCR rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi d  w  vx rc ¼ p  vCR es ¼

ð4Þ ð5Þ

PT, Px and Pz are the torsional, transverse and axial power components. n is the rotational speed, T is the measured torque, and Fx and Fz are the reaction forces in x and z directions. According to the method of Fukakusa [2], the corrected radius rc was substituted into Eq. (4). This corrected radius refers to the inner volume of the stud, which is deposited as coating, while the outer stud volume makes up the flash [2]. The model used in this study is described in more detail by Hanke [6]. Temperature measurements were conducted with type K sheath thermocouples having diameters of 0.5 mm. According to the standard [DIN EN 60584-1], the accuracy in the range of −40 to 1200 °C is ±0.0075  Tmeasured (measured temperature). The data acquisition system

including the software by the company National Instruments (Austin, USA) provided sampling rates up to 100 Hz. Holes were drilled into the bottom of the substrate along the deposition trajectory, up to a depth of 7.5 mm. For the 8 mm thick sheets, the tips of the thermocouples were therefore placed 0.5 mm below the substrate surface. Silver thermally conductive paste was used to enhance the conductivity between the tip of the thermocouples and the bulk material within the holes. In addition an infrared camera ImageIR 8300 (Infra Tec GmbH, Dresden, Germany) measured the temperature on the studs (including flash) and coatings’ surface from the direction perpendicular to the machine table’s x-axis. During the process the camera captured thermographs with a sampling rate of 30 fps. The calibrated temperature range was configured to 150–650 °C. Due to errors caused by e.g. reflection, different surface roughness, oxide films or measurement angles, the obtained data was processed considering comparative temperatures of different welds. For the analysis of layer and substrate characteristics, samples were cut from the middle of the coatings, perpendicular to the translational welding direction. These cross sections were then prepared (including embedding, grinding, polishing) according to metallographic standards. Optical microscopy was performed using LEICA DMI 5000 M.

Results and Discussion The main process parameters axial force (Fz), translational speed (vx), and rotational speed (n) were varied until layers of the AA 6060 base material alloy could be deposited homogeneously and stationary. The following process parameters have proved to be suitable: Fz = 4.5 kN, vx = 15 mm s−1 and n = 4000 min−1. They were then applied to all other alloys, too. The layer geometry (width (w) between 22 and 25 mm, layer thickness (d) between 3 and 4.5 mm) and specific energy input per volume (es) (between 6 and 8 J/mm3) obtained for AA 6060 were then aimed for all other alloys by adjusting the process parameters accordingly. The parameters established to generate these comparable coatings, which are presented in the following are given in Table 2. In Fig. 2 light microscopic images of cross sections from coatings from all alloys, produced by the parameters, optimized for the original AA 6060 alloy (Fz = 4.5 kN, vx = 15 mm s−1 and N = 4000 min−1) are presented. It is obvious that the addition of the alloying elements has a strong effect on the obtained coating geometries. While the pure AA 6060 alloy generates a very thick coating layer, the addition of either Mg or Si leads to a significant decrease of the deposited volume.

360 Table 2 Suitable process parameters to reach comparable process characteristics

J. Ehrich et al. Material

vx translational speed (mm−s)

n rotational speed (min−1)

Fz axial force (kN)

AA 6060 wrought

15

4000

4.5

AA 6060 cast

15

4000

4.5

AA 6060 2% Mg

12

1500

11

AA 6060 3.5% Mg

8

1000

11

AA 6060 6.6% Si

12

1800

9

AA 6060 10.4% Si

12

1600

9

AA 6060 14.6% Si

14

1500

9

Fig. 2 Cross sections of layers deposited using constant process parameters (Fz = 4.5 kN, vx = 15 mm s−1 and n = 4000 min−1)

The dimensions of all generated coating layers, i.e. width and thickness, are presented in the graph in Fig. 3. No difference in coating dimensions between the cast and the wrought state of AA 6060 was observed. Considering the low content in alloying elements and therefore small amount of secondary phases, which will differ between the two material states, this finding is not surprising. It appears that differences in grain size and morphology, which will also prevail between the two states, do not play a significant role in FS of this alloy. The addition of 2 and 3.5% Mg leads to a decrease in thickness and width for the same process parameters, which is more pronounced for the higher Mg content. The presence of Si also leads to smaller coating dimensions, which also decrease with increasing Si content. Still, the difference between 6.6 and 14.6% Si is not as pronounced as in the case of Mg. For all alloys it was possible to generate coatings of equal or similar thickness and width related to the original AA 6060 alloy. As shown above in Table 2, it was necessary to adjust the process parameters. For both groups of alloys, the

axial forces had to be increased (for Mg-addition to 11 kN and for Si-addition to 9 kN) in order to ensure a homogeneous material deposition with a constant consumption rate. With a stable process control, the translatory movement can be used to control the thickness and width of the coating within a specific range. Generally, as the translational speed decreases, the width and thickness of the layer increase. Here, vx had to be reduced from 15 mm s−1, 2% Mg to 12 mm s−1 and for 3.5% Mg to 8 mm s−1. Regarding the translational speed, a small upward trend can be observed for the Si-alloys. For 6.6 and 10.4% Si vx of 12 mm s−1 proved to be suitable, for 14.6% Si vx was increased to 14 mm s−1. The most significant adjustments in process parameters were made with regard to rotational speed. An increase in the Si content requires a reduction in the rotational speed (6.6% Si: 1800 min−1, 10.4% Si: 1600 min−1 and 14.6% Si: 1500 min−1). For the Mg-alloys, this trend is more pronounced. This results in a rotational speed of 1500 min−1 for 2% Mg and a speed of 1000 min−1 for 3.5% Mg. Those trends are summarized in Fig. 3.

Effect of Mg and Si Content in Aluminum Alloys …

Fig. 3 Layer dimensions of coating deposited using constant process parameters and variable process parameters (acc. to Table 2) for all alloys

The process temperatures measured with thermocouples type K are presented in Fig. 4. The average of maximum values of three thermocouples for each surfacing process are plotted. Three thermocouples measured the temperature 0.5 mm underneath the substrate surface within the deposition steady state regime. Based on the same temperature measurement method among all coatings, the values may be compared and correlated with each other. The highest process temperatures prevail in the shear zone above the deposition material, which is considered to be complex to measure. Using the IR camera it is at least possible to measure a part of the stud’s circumference, taking into account sources of errors (described in the previous chapter), see Fig. 5. When processing the Mg-rich alloys more heat is

Fig. 5 Measuring the temperature using an IR-camera during the FS process. Constant parameters used for both alloys (Left: 14.6% Si, Right: 2% Mg)

361

Fig. 4 Average of maximum process temperature 0.5 mm underneath the substrate surface measured using three thermocouples type K

generated than in case of the Si-rich alloys, whether the parameters are kept constant or not. This behavior is reflected for both measurements methods, with the thermocouples (below the substrate) and by means of thermograms (surface of substrate, layer and stud). Due to the high fraction of hard phases in the Si-containing alloys, a higher temperature development and higher flow stresses would have been expected, hard phases acting as another source of internal friction during steady state plastic deformation. However, the graph in Fig. 4 shows for both constant parameters and the adapted process parameters that the temperature development below the layer is clearly higher than for the high-Mg alloys. With regard to the temperature development, the 2% Mg and 3.5% Mg alloy behave antiproportionally to the 6.6% Si, 10.4% Si and

362

14.6% Si alloys. As the magnesium content increases, the heat input increases. This behavior can also be confirmed analyzing the thermograms. As an example, Fig. 5 shows that for the 2% Mg alloy in the region of the stud tip, nearby the shear zone, a higher temperature is present than for the 14.6% Si alloy. In Fig. 6, the deposition efficiency η and the specific energy input per volume es, are presented. Deposition efficiency and specific energy input per volume unit behave reciprocally to each other. Thus, layers with smaller dimensions, generated using constant parameters, result in lower efficiencies and higher energies required. For the layers with a slightly larger volume, higher efficiencies and smaller energies are also obtained. The coating volumes for 2% Mg and the alloys containing Si are in the same order of magnitude, so that similar efficiencies and energies can be achieved even with constant parameters. The efficiencies for variable parameters lie in the range of 40–53% across all alloys and the energies in a range of 5.8–8.8 J/mm3. The efficiencies and energies of the layers with constant parameters correlate directly with the associated layer geometries. The layers generated with variable parameters show comparable values for η and es for all alloys.

J. Ehrich et al.

It stands out from the presented results, that the addition of Si in the three amounts used in this study shows clear trends in its effects on the FS process and the obtained coatings. For Mg, this is not the case. Increasing the Mg content requires a reduction in processing speed or leads to thinner coatings, as already observed in [6]. Nevertheless, the addition of 2% Mg leads to reductions in process temperatures and deposition efficiency, while increasing the Mg content further to 3.5% reverses this trend. It is known that Mg is not only effective in solid solution strengthening in Al, but it also affects the stacking fault energy and the dislocation structures formed upon plastic deformation [9, 10]. For example in [10], after tensile tests on binary Al alloys with 3–10% Mg it was observed, that pure Al formed clearly observable dislocation cells with sharply defined walls and dislocation-free interiors. With 3% Mg, dislocation tangles were found, distributing dislocations throughout the crystals. With Mg content larger than 3%, the tangled dislocations formed high-density band structures, corresponding to pronounced strain hardening [10]. Processing conditions during FS deviate significantly in temperature, strain rate and total strain from a tensile test. Still, it is reasonable to assume that changes in dislocation behavior under deformation may have a strong effect on DRX with complex interactions of the processing conditions, recovery or recrystallization mechanisms and flow stresses during deposition. Si on the other hand is insoluble at room temperature, and soluble only 1 µm) act as nucleation sites of recrystallization and small particles (400 °C and for Al6Fe >580 °C. The thermostability

Mechanical Properties Evolution for 8xxx Foil Stock …

of the single phases was described to be independent of the formation circumstances [23]. In 1xxx alloys soluted Fe precipitates from a supersaturated state, forming Al3Fe, a-AlFeSi, and Si phases during annealing (different precipitation temperatures were reported). Si and a-AlFeSi precipitate mainly during the recrystallization process and Al3Fe occurred mainly after the completion of recrystallization. Due to the increased deformation, the precipitates form on features of the deformation structure like micro-shear bands and lamellar boundaries (low diffusivity of Fe favor precipitation). The softening is faster after sufficient deformation and annealing [41, 42]. Figure 5 shows the microstructures of two Al-Fe-Si low-content alloys after pre-heating at 630 °C for 12 h. Compared to the as cast state (Fig. 3), the constituents underwent a phase transformation and additionally, their morphology changed. The pre-heating caused a phase transformation from the metastable AlmFe or a-AlFeSi phase to the equilibrium Al3Fe phase (via a dissolution reprecipitation mechanism at different temperature >550 °C) [33]. Typically, in the AA 8079 alloy highly elongated Al3Fe constituent particles are present, which are harmful for formability. During pre-heating up to 600 °C, the Al3Fe constituents remain largely unaffected and their morphology hardly changes. Otherwise, in the Si rich AA 8011 alloy (showing needle-shaped Al3Fe and “skeleton like” a-AlFeSi particles) the a-AlFeSi constituents spheroidized, whereas the Al3Fe particles were transformed via b-AlFeSi to a-AlFeSi during pre-heating. The transformation and the changed constituent morphology might be the reason for the good ductility of AA 8011 [34]. Alloy AA 8006 contains Al6(Mn,Fe) and Al3(Fe,Mn) constituents as second-phase particles. Al3(Fe,Mn) particles are more irregularly shaped (Fe:Mn ratio >10) and small, roundish Al6(Mn,Fe) phases with (Fe:Mn ratio 550 °C). During pre-heating at 500 °C a few plate-like a-Al(Fe,Mn)Si dispersoids were observed. Annealing at 500–550 °C lead to the formation of a small fraction of dispersoids, mostly Al3Fe (needle or plate-like morphology). A two-step homogenization practice was shown to support the uniform distribution of compact Al3Fe dispersoids with lower density and larger size. The volume fraction of dispersoids formed during pre-heating is larger in AA 8011 than in AA 8079. In AA 8011, only dispersoids of the a-AlFeSi type or its isostructural Mn bearing variant a-Al(Fe,Mn)Si were obtained [34]. The AA 8006 alloy contains a-Al(Fe,Mn)Si dispersoids, which volume strongly depend on the time/temperature cycle of the pre-heating. At low temperatures, a-dispersoids are heavily precipitated. With increasing temperatures (>500 °C), these a-dispersoids re-dissolve and re-increase the solid solution content of the contained elements. Simultaneously, the pre-existing constituent phases grow, leading to a formation of very fine a-phase dispersoids during back-annealing after cold rolling. Engler et al. prefer a two-step homogenization to attain a low Zener drag and a low driving pressure for continuous precipitation, leading to a fine-grained microstructure and a characteristic particle stimulated nucleation recrystallization texture [35]. Solutes: To consider the influence of thermo-mechanical processing, several authors [1, 10, 34, 35] applied simulation models (e.g. the numerical ClaNG-model, which predicts the microchemistry based on the theory of nucleation and growth of secondary phases and multi-component thermodynamics). Generally, it must be stated that the local cooling rate changes the solute content within casted slabs [32]. The content of Fe in solid solution increases with increasing cooling rates. The Fe content in the solute solution depends

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further on the Fe content of the alloy (higher Fe levels increase supersaturation) and Si addition (Si reduces supersaturation of Fe) [43]. Relationships between electrical conductivity and Fe or Si contents are quasi-linear, whereas Si decreases conductivity and increases Vickers hardness stronger than Fe. The electrical conductivity of Al-Fe-Si alloys increases during homogenization, due to changed alloying element content in solid solution and in Al-Fe-Si phases [44]. Already during the heat up phase of the pre-heating, the solute level decreases. First, dispersoids form, due to a rapid depletion of the oversaturated solid solution. When the metal temperature is >500 °C, the solid solubility of Fe and Si increases and Al-Fe-Si phases partly dissolute again (the solid solution levels progressively increase). The highest solute level is obtained after homogenization with the highest soaking temperature. After pre-heating, the slabs temperature decreases to *450 °C and the solubility of the alloying elements decreases, likewise. The depletion is incomplete and a considerable share of solute elements remains in the Al matrix, leading to an increase of solute drag and therefore, modify the softening behavior (suppress recrystallization after hot rolling) [1, 10, 33]. Lok et al. [45] have shown that during hot deformation the solute levels of Fe and Si in the Al matrix decrease, whereas during cold deformation, the solute levels remain unchanged. The most inter-annealing conditions (at 300–400 °C) promote the precipitation of secondary Al-Fe-Si phases, resulting in a decrease of elements in solute solution. For sheets with initially different solute concentrations, similar solute levels are obtained by inter-annealing. The highest solute level (therefore, the highest solute drag) is gained by a process route skipping the intermediate annealing (shifting softening to higher temperatures and retard softening during final annealing) [1]. Hasenclever [16] has shown that there is a clear relationship between tensile strength and Fe solute content, whereas the tensile strength increases with higher solute levels.

Experimental Results Performing a research on AA 8021 alloys with varied chemical composition (Table 2), the focus was on the influence of the Fe-content on the mechanical properties. The material was produced according to the experimental practice (Fig. 6) using DC-cast rolling ingots. Table 2 Chemical composition of two AA 8021 alloys

Fig. 6 Experimental procedure

Fig. 7 Fe-content influence on strength and elongation (AA 8021 foils; O-temper)

The material was cold rolled to a final thickness of about 50 µm and soft annealed. At the final thickness, the mechanical properties were determined by performing tensile tests and the grain structure was investigated on the surface. The influence of the Fe-content on the tensile strength and elongation in the O-temper condition is shown in Fig. 7 (determined at 0° to the rolling direction). The results confirm the findings by Hasenclever et al. [4–7] and they show that the alloy composition has a positive effect on strength and elongation behavior. The grain structure and number of particles (constituent and dispersoids) are known to be related to the resulting final properties. Generally, the number of particles increase with an increasing Fe content [5]. With increasing Fe content, the tensile strength and elongation, increase in the O-temper condition and further the resulting grain size is fine and uniform. The resulting

No.

Alloy

Fe (wt%)

Si (wt%)

Mn (wt%)

1

AA 8021

1.35