A PORTION OF THE NICKEL ALUMINUM EQUILIBRIUM DIAGRAM

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A PORTION OF THE NICKEL ALUMINUM EQUILIBRIUM DIAGRAM

A Thesis Submitted to the Faculty of Purdue University byRobert George TJlrech

In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August, 1950

PURDUE UNIVERSITY

THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION

by

______________ Robert

e n title d

George UIre ch.

A Portion of tbe N ieke1-Aluminum Phase Diagram

COMPLIES WITH THE UNIVERSITY REGULATIONS ON GRADUATION THESES

AND IS APPROVED BY ME AS FULFILLLYG THIS PART OF THE REQUIREMENTS

FOR THE DEGREE OF

Doctor of PhiLoao-phy

P r o f e s s o r i n Ch a r o e o f T h e s i s

H ea b o f s c h o o l o r D e p a r t m e n t

/ ^ Y ] .

h

is

O

TO THE LIBRARIANS----THIS THESIS IS NOT TO BE REGARDED AS CONFIDENTIAL.

^

GRAD, SCHOOL FORM 9—3 - 4 8 — 1M

Z

A

PBOrasSOB ZZrjQHAB#Ei

TAB IE OP CONTENTS Page ABSTRACT

INTRODUCTION • • • • • »

•••••*••• •*»•***»»««•* ••*•••••••

1

Surray of tha Literature*******.***..*.**.*..,.,,*

3

EXPERIMENTAL. • • • • • •••••»•••••••••*•..•.••.... ......*..*

7

Theory of loaduetion Seating and Melting..*.......,

7

General I

n

f

o

n

a

a

t

i

o

n

.

23

Furnaee Construotioii.**...*.***.***.........

25

Coil Design.^*.*•••»*•••*•*•••*.•••*.•••.•••••«••«•

28

Method of A n a l y s i s and the Plotting of Data ••...*•

29

Thermocouples ***«»«.*•• •*•«**.*..»**•*.«.*»».**•.*

35

Refractories *••••*••• •»*••••••••••••••••••••«••*.*

36

Preparation, o f the Alloys*******.*..*****.*.*...**

37

Chemical A n w l y s i s . * . ....**.*...♦.*.*.**»...*♦.*.*♦

38

Microaoopio

Investigation**.***..*.*.*******.*****

40

Preoipitaticm Hardening Experiments•••••••••*••••*

41

Experimental Results••*•*•••••••.•••••.•••••••••*.

42

Hardness M e a s u r e m e n t s •*••••••••••••••••••«•••••*•*

43

Precipitation Hardening Results.........••«*.*•••*

46

DISCUSSION OF R E S U L T S . * . . * . . . .....

73

CONCLUSIONS*** • • • • • • • • • *

76

APPENDIX.***.,*•*«.*•**««•*.••«•«•«•• ••*••**•*. **«••***«••

i

Design of Coil******«.****.*******«*...•*.*•****•*

1

Analytical Procedure using Dimethylglyoxime..*...«

ix

I a t e m a t i o n a l Nickel*s Analyses.**••••*••.**.••••*

x

b ib l io g r a p h y .

Xi

TABLE — the resistance function (a function of the index ratio) Each of the resistance factors as indicated above are fundtiona of the particular index ratio for that specific shape, and approporiat© graphs or equations for these values can be found in most texts on induction heating*

In these studies the effective charge shape was

§ hollow cylindrical charge since a carbon heater sleeve was used as the principle charge*

The resistance function for a hollow oharge

is defined by the equation which followss

r f r - f e m h ' \ + s i n A ) + Z K ( * t n h /) - s / n * ) c o s o) ( o > * h /\- C J > s r i J t+ c o s r \ ) +-2K C s i ' l h f ) -S/risy) In this expression /\

is the index ratio given in equation (lie)

where

a

—

the radius of the charge in cm

t

-

the wall thickness in cm

By substituting the values of the resistance function and the shape factor In the equation for the heat developed (equation 6) the follow* lug equation is obtained s

HZ { M

- f~

f

&

CL * £ M s* *

io7

(12)

19

This equation can further he reduced by substituting the expression for magnetising force •h * with the result that the final expression for the rate of heat developed in a charge using external eoils then becomes

p_ i

/

Jt

7 *

N

*a-

**

fl3l

to*

For index ratios greater than 3 this equation is the same as that for solid charges of the same radius end material* The distribution of heat developed by eddy currents in a oh&rge

is the same as that of the magnetic flux induced therein*

heat distribution is given another nsme*«heat concentration*

This

It can

be controlled to any desired value by using the proper frequenoy* The rate of temperature rise in a charge for a given applied voltage depends on a number of factors« 1*

The efficiency

2*

The rate of heat loss

3*

The thermal properties of the material in the charge

4*

The surfaeeovolume ratio of the charge

The aurfaoe»volume ratio in this case is the ratio of the lateral surface area (neglecting the ends) to the volume*

With charges having

relatively small base dimensions (i*e* radius or half thickness) the lateral surfaee area is much more important than, the thermal diffusivity as regards heating*

AM the base dimension increases* however® the

thermal diffusivity becomes the controlling factor* The heat content of the charge material determines to a considerable extent the heating characteristics of an induction unit* By heat content is meant the unit quantity of heat absorbed .by a material

20

for a given rise la temperature in degrees 0*

This value een be cal­

culated. using the oonveutiemal expression

%= vhere

Ziif.

~

^

(watt-hoursy#)

(14)

S*v, = the mean, specific heat over the temperature range t* L

-

the latent heat if any in w att sfcours^fr

With few exceptions (thlvr work presents one of these exceptions) considerable heat losses are encountered in most induction heating and Melting operations*

Most ef these heat losses* particularly at elevated

temperatures, are due to radiation although there is a considerable amount of heat loss by conduction*

The rate of heat loss by radiation

is given by the equation

P= P=

where

.si ^ ( t £ - -rkV 3-6>B

o

IO IO

UJ

o

o o

o

CM

QC 3 o

CP IO

o

z o

ro

o CM

o

IO to

o IO IO

IO

s n o A im w

TIME - SECONDS

INVERSE

RATE

IO

35 T.bl.

2

Sampl. Data Sliaat for Dlffereati&l Thermal Analysis m

34*00 •05 •10 .15 •20 •25 .30 •35 •40 •45 •50 •55 •60 .65 •70 •75 •30 •85 •90 •95 35.00 •05 •10 •15 •20 •25 •30 •35 •40 10 • •50 •55 •60 •65 •70 •75 •30 •85 •90 •95 36.00 •05 •10 •15 •20 •25 •30 •55 •40 •45

Galr. 20.9 20.7 20.6 19.9 19*8 19*5 19.5 18.2 18.8 18.5 18*2 18*0 17.8 17.5 17.2 16.9 16 .6 16.4 16.2 16.0 15.9 15.8 15.3 16.0 14.7 14.6 14.4 14.2 13.9 13.9 13.6 13.2 13.0 12.8 12.5 12,3 12.1 11.9 11.6 11.5 11.4 11*3 U.O 12.8 10.6 10.5 10.2 10.1 9.8 9.6

wr

•50 .56 .60 •65 ♦70 *76 .80 .85 .90 .95 37.00 •05 .10 •15 •20 •25 .30 .35 .40 .45 •SO .55 .60 •65 .7© .75 .80 .85 .90 .95 38.00 •05 •10 •15 .20 .25 .30 •35 .40 •46 *50 •56 •60 .66 •7© *76 .80 .85 .90 .95

Oalir. 9.4 9*4 9.2 sl 8.7 8.5 8.5 8.1 8.0 7.8 7.6 7.5 7.3 7.1 7.0 6 .8 6.6 6.4 6*2 6*1 6.0 6*8 5.6 5.5 5.3 5.2 5.0 4.8 4.7 4.6 4*4 4.2 3.9 3.7 3.6 3.5 3.4 3.2 3.0 2.9 2.7 2*6 2.6 2.3 2.1 2.0 1.0 1.8 1.6 1«5

m 39.00 •OS •10 .15 •20 .25 •30 .35 •40 •45 •50 •55 *60 •65 .70 .75 .80 •85 .90 .95 40.00 •05 •10 .15 .2© .26 •30 .35 .40 •45 .50 .60 .65 •70 •75 •80 .35 •90 .95 41.00 •05 .10 .15 .20 .25 .30 •36 *40 .45 .50

Oalv.

117

Galv.

1*4

.56 •60 •65 .70 •75 •80 •86 •90 •96 42.00 .05 #1© •15 •20 .25 •30 •35 •40 •45 •SO .55 .60 .65 .70 .76 •SO •85 .90 .95 43.00 •05 .10 .15 •20 .25 .50 .55 .40 •46 .50 .55 .60 .65 .70 .75 •80 •85 •90 •95 44.00

-2.4 •2«4 -2«4 -2.4 —2.4 -2.4 -2.3 —2.5 -2.3 -2.1 -2.1 -2.1 -2*1 —2.0 -2«0 -1.9 —1.8 -1.8 —1*7 -1.7 -1.6 -1.7 -1.7 -1.7 -1,7 -1.7 -1.8 -1.8 -1.9 -1.9 -2.1 -2.2 -2.4 -2.6 -2.5 -2.6 -3.0 -3*3 -3.5 -3.8 —3.9 -4.0 —4.0 —4.0 -4.0 -4.0 •4.0 -4.0 -4.0 —4.0

ImZ 1.1 1.0 *9 .7 .6 •5 •4 •3 .1 0.0 0.0 •1 •2 •3 *4 •4 •5 .6 .7 •8 4«0 -1.0 -1.1 -1.2 -1.2 -1.4 —1.4 -1.6 -1.5 -1.6 -1.7 -1.8 -1.8 -1.9 -1.9 -1.9 -2.0 -2.0 —2.1 -2.1 -2.1 -2.2 -2.2 -2.3 -2.3 -2.3 —2.5 -2.4

34

D IFFER ENTIAL THERM AL ANALYSIS 45

44

43

42 MI LLI VOLTS

H E A T IN G

CURVE

41

40

39

38 “3

-2

1

J-

1

-I

0

1 2

G A LVA N O M ETER Fig. 11

1

1

1

_L

3

4

5

D E FLE C TIO N

$6

only be true if the specific heats and the a i m w r y nearly the same*

of the tiro bodies ere

At the brans formation point or at any other

point wherein a ehange of state occurs in the specimen the differeaoe in temperature between the specimen and the neutral body will increase rather abruptly and the offoots of the rate of heating or the rate of cooling will hare little or no influence on the results*

In recording

and plotting this data the temperature difference between the specimen and the neutral body is plotted against the upper temperature value of the temperature interval for cooling data and against the lower temperature value for heating data*

Examples of recording and plotting

thermal data by this method are: present in Table 2 and Figure 11*

Thermocouples Two different types ef thermocouples were employed in the determination of this diagram*

For liquidus and solidus determinations

and, in general* for all work requiring temperature measurements above 1200° C** a 22 gauge platinun-platinum rhodium thermocouple was used* This thermocouple was calibrated using pure nickel and pure copper as the standards*

Preliminary studies indicated that the calibration

curve obtained so elesely matched that furnished with the thermocouple that all future determinations were made using the prepared calibration curve*

Practically no variation occurred in the thermocouple ealibra*

tion curve over the entire course of this investigation* For solid solubility determinations a 22 gauge chromel-alumel thermocouple was used*

type of thermocouple was employed with

the derived differential setup and in all cases where temperature measurements were made below 12©0° C*

Ho external protection was used

56

to prevent oxidation during the runs*

la calibrating this thermocouple

puro load, aluminum, and copper were used.

Initial experiments on

the calibration of* this thermocouple indicated that it vas reading about 6° C* high.

This vas corrected by annealing the vire for five

hours at 1200° F* to redoes the draviag strains and the internal •tresses doe to coiling*

Refractories Many difficulties resulted from the lack of satisfactory refractory materials for containing the melts*

the greatest refractory

problems, as vould be expected, occurred in those elements of the fur* naoe which were in direct contact with the liquid metal*

Same diffi­

culty vas experienced in obtaining a suitable refractory material for use as the furnace lining since in this work the furnace refractory was forced to serve mot only as a heat resisting lining but also j|s a thermal insulator*

Ibis problem vas finally solved by using powdered

perielase which is essentially a high purity magnesium oxide*

Unfort­

unately most of the commercially available refractories recommended for high temperature melting contain silicon which reacts readily with aluminum at elevated temperatures*

Carbon or graphite crucibles were

most satisfactory for containing these melts $ however, the possibility of carbon plek—up b y the molten nickel eliminated this possibility* iluadum crucibles prepared from an Si 221 mixture vers found to be very satisfactory but were commercially unavailable in the sised required for these melts*

is a result it vas found that Plumbago crucibles

coated with slurry of alundum cement, mixture Bi 518, sould be used satisfactorily.

In addition to being quite inert to the molten metal

37

these crucibles offered th» additional tdnat&gvs uteoisted with conducting crucibles*

Ho earbss pdek»up was experienced in the melt**

ing operation although the crucibles required a near aluwdun coating

after each melt because of a tendency on the part of the alundum. coat* lag to erase or spall as a result of the difference in the eoefflelents of expansion between the eoating and the graphite orueible* Sillimanite protection tubes were employed as the external protection for the platinum»platinum rhodium thermocouple in determining the liquidus end the solidus curves*

The ends of these tubes were

coated before each run with a thin wash of alundum cement mixture B A 518* in order to prevent any possible reaction between the protection tube and the molten aluminum*

Preparation of the Alloys The synthesis of the alloys used in this work was somewhat complicated by the fact that aluminum is easily oxidised and the result* lag film is tough and tenacious and extremely difficult to break up to insure complete alloying of the constituents*

In addition to this*

the wide difference in the melting points of the -tor© pure elements (nickel - 1458° C** and aluminum - 660° C*) served to intensify this tendency because of the necessity of superheating the aluminum approxi* mately 800° C* before complete alloying was assured*

This difficulty

was largely overcome by using an inert atmosphere of helium and a special flushing technique involvidg the placing of aa alundum coated sIllimanite lead*ia tube in the hottest of the crucible and then loading the solid aluminum metal owd nickel shot in around the tube* then sealed

Bic furnace was

the system was flushed with helium at a rate of flow

S3

of 300 liters per minute*

A. positive pressure was Maintained in the

furnace by means of a manometer attached to the lead-in tube* exoaped through the various openings in the furnace lid*

The gas

ifter

flushing the furnace for the desired length of tine, the gas floe vas reduced to 30 liters per minute and the inert gas lead-in tube was with* drawn from the loose metal charge to a position approximately one centi— meter above the surface of the charge*

Halting proceded as rapidly as

possible to further minimise oxidation* The alloys were synthesised from Hand nickel shot with a purity of 99*9?S*

The principle impurities in the nickel ware carbon

(*055%) and Fe (*034^)*

The aluminum used was 99*99^ pure with Fe

(*009$ and Si (*001890 as the principle contaminants *

Chemical Analysis Chemical analyses were run on all the alloys prepared and used in the determination of this diagram*

The method of analysis

employed was the standard gravimetric procedure with dimethylglyoxime * A more detailed description of this procedure is given in the appendix* Table 3 gives the results of the analytical work on these alloys*

For

the most part the composition of the alloys after smiting approached the nominal composition quite closely*

The principle cause for the

difference in these values was probably due to losses incurred in melting*

As the nickel content of the alloys was decreased these smit­

ing losses increased from a value of about 0*5^ for the alloy containing 959S nickel to a value of about 4.2JS for the alloy containing 8(# nickel*

89

Table

8

Results of Chemical Analysis

Ingot

ffominal ooap. niekel

Actual comp. % niekel .

Are. % niekel

95*0

94.98

94.52

94.60

94.7

#3

92*5

91.96

92.08

91.92

91.99

|4

90.0

89.04

88.96

89*04

89.01

#6

89.0

88.00

88.20

88.40

88.20

#•

88*5

87.78

87.74

87.90

87.80

#7

86.7

86*1

86 .0

86.0

66.0

#6

86.0

84.9

84.80

84.6

84.80

#9

85.0

84.9

84.7

84.8

84.20

#10

83.5

83.8

84.0

84.3

84.00

#12

80.0

79.6

79.8

79.7

79.70

#13

94.0

94.0

94.3

94.1

94.10

#14

93.0

93.2

93.0

93.0

93.10

#15

92.0

92.2

92.2

92*3

92.30

#16

91.0

91.0

91.2

91.0

01.10

A©

Some difficulty was. experienced in drilling and outting these alloys*

On on# hand* the

solid solution, alloys containing freon

90-100^ niekel wore rather gummy and were drilled only with considerable difficulty* machine *

They were* however* quite easily machined on a milling

On the other hand* alloys containing from 80-8

impossible to cut even on a milling maohine*

nickel were

This was due* no doubt

to the presence in these alloys of an extremely hard constituent* Hill* which completely ruins a high-speed steel milling cutter in a very short time*

These alloys were successfully sectioned on a high speed*

water cooled* alundum cut-off wheel without much difficulty*

Hierosoopie Investigation Microscopic studies were employed in this investigation to determine the solid solubility of these alloys and* in addition* to cheek the euteetie temperature and the limits of the eutectic arrest* In determining the solid solubility of these alloys* samples were cut from the cooling curve ingots and subjected to heat treatments at var­ ious temperatures*

The samples were quenched in water from these temp­

eratures and examined microsoopiely*

In addition* hardness readings

ware obtained on each sample immediately after quenching* The preparation of the alloys for polishing and etching prior to microscopic examination was quite simple once the alloys had been sectioned*

A. Selvyt polishing cloth impregnated with alumina was used

as the rough polishing medium after the samples had been ground by hand to number 000 abrasive paper*

As the final polishing operation the alloys

were taken to a Micro cloth impregnated with Bushier gamma alumina $S* Several etchants were tested in an effort to find a positive

41

identification for all ihe constituents present*

in etchant consist—

ing of oono entrated aitris no id and glacial aeatie aoid in equal pro* portions and dilated to the desired concentration with either water* glycerine* or aoetono vas found to to quite useful as a grain boundary etch but was entirely unsatisfactory in distinguishing the different phases present*

Considerably better success w&a encountered with

Sohran*s reagent which consists of 15 grans of ferric ohloride* 3 grans of ouprie asnoniun chloride* 50 ml* of hydrochloric acid* and 25 ml* of water*

This reagent not only provided better grain contrast but

also successfully distinguished the HiAl phase from the os. solid solu­ tion phase*

A modified Sohr am *s etchant consisting of one part of 1€%

Fe2(N03 )3 and two parts of Schramms reagent was used with only moderate success* Precipitation Hardening Experiments Previous work by Alexander and Vaughn presented in Figure 3 (sad later confirmed by the current investigation) indicated that these alloys might be susoeptible to precipitation hardening treatments in view of the decreasing solubility of aluminum in niekel in the alloys containing from 90—10056 nickel*

Several experiments were conducted*

therefore* to determine exactly how susceptible these alloys were to suoh treatments*

An alloy containing 92% nickel was heated to 125©°

C* for 24 hours and quenched in water*

The alloy was theaaged at

500® C* for various periods of time and hardness readings were recorded* The results indicated that this alloy was only mildly responsive to precipitation hardening treatments and as a result no further attempts were conducted along these lines*

42

Experimental Result* The results of the thermal analysis of the nickel-rich portion of th® niokol«tl\niiiua ofnilibriu ditgriu Table 4«

prostntod in

The liquidus Mad the solidna Ttlnet g i n a In tho table are

average* of tho boating aad oooling ourve results*

In soot oases*

the liquidus temperature (and solidus temperature) obtained from the heating ourve data wne frees 16-20° C* higher than that obtained from the oooling ourve data*

Thermal arreete characterlatie of euteotio

type alloy* were obtained in alloys ranging in composition from 84c% to 90# niekel*

Tho alloy with 86*0# niekel content showed an extended

thermal arrest both in the oooling aad the heating ourve indicating it to be elose to the euteotio composition. arrest were determined microscopically*

The limits of the euteetie

For reasons of comparison the

results of the work of Alexander and Vaughn sure incorporated in this table* The results of the mleroaeopie analysis sure presented in Figure 12 along with the results of the thermal analysis*

The micro­

scopic results sure represented by a series of dots indicating the single and the duplex alleys*

The results of the tiro methods of

analysis indicate that the region of the nioke 1-aluminum equilibrium diagram from the internetallio compound composition to 1O0# niekel is a limited solid solution type of diagram*

The euteotio composition

appears to be very oloao to 86^ niekel and the limits of the euteotio alloys in the region of the euteotio temperature appears to be 82*5# and 88*5# nickel* analysis

The euteetie temperature as determined by thermal

the average of the heating and the cooling curve results

43

was found to be 1360° C*

This temperature was reoheoked by- microscopic

examination and found to b a 1363° C*

The limits of the solubility of

aluminum in niokal as dsttraiasd b y miorosoopio means aad reoheoked by tha derived differential mobbed of tfasnal analysis ora presented in T a b la &•

The limits of tha s olid aolubility of aluminum in nickel aa

given in tha ▲•S»X. Handbook (13) are Incorporated in this tabla for purposes of comparisons

Hardness Measurements Hardness readings mere taken on all alloys ,in the "as east1* and in the quenched condition.

Table 6 gives the graphical represen-

tation of this data for several alloys over the entire range of heat* treatments*

In the duplex alloys in the eutectic region of the dia­

gram, little inorease in hardness was obtained by quenching from ele­ vated temperatures*

la the region of the intermediate phase* a rather

marked inorease In hardness was obtained by quenching these alloys from temperatures in excess of 1300° C*

The maximum hardness obtained

in the solid solution type alleys was obtained in those alloys in the range of 90-92% nickel when quenched from temperatures between 1230* C. and 1365° C*

Id the alloys containing large amounts of the Nill

intermediate phase the maximum hardness was developed in the alleys containing 79-32£ niekel when quenched from temperatures between I860* 0* and 1390° C*

The hardness obtained in these alloys ranged from

Rockwell C— 52 to G-61 which approaches the hardness of quenched high oarbon steel*

In addition the mier©structures of these alloys posses

■ftw same needle-like appearance as those found in msrtensitic steels*

A PORTION

NI-AL If)

THE Q UJ CO

OF LU QT

>

WGT % NICKEL

DIAGRAM

44

o

3Un±VU3d\H3±

45

Tabla

4

U q a l d w and 8olidua loqptratart l a t h o r ^ Basalts

Wgt. % Hieksl

Liqttidus Trap.

100

1455 0

94*9

1457 G

92.0

Alaxandar sad Vaugha Basalt*

8olidas Trap.

Wgt. * Xlekel

Liquidus Trap*

Solidus Trap.

100

1452 C

1425 C

95

1451 C

1429 C

1412 C

92*5

1414 C

69.0

1405 C

1574 G

90.0

1591 C

88.2

1595 G

1561 G

89.0

1584 C

87.6

1587 C

1558 G

88.5

1578 C

86.0

1587 C

1557 C

86.7

1365 C

84.8

1591 C

1558 C

86.0

1579 e

1562 C

84.2

1420 G

1557 C

85.0

1424 C

1554 C

84.0

1424 C

1562 G

85.5

1451 C

1357 C

81.7

1488 C

1412 G

82.0

1458 6

1347 C

79.7

1550 C

1475 C

80.0

1531 0

1560 C

46

Precipitation Hardening Results

The results of the work on the precipitation hardening investigations are given in Table 5.

These results indicate that

the maximum hardness developed in the solid solution type alloy con­ taining 92£ nickel was *>eut Reokwell B-88 te B-94.

This is an average

increase in hardness of about 28%t and occurs after an aging period of fron 8—1© hours at BOO® C*

Apparently only a very slight inorease

in hardness is obtained on aging these alloys at roooa temperature even after one month* Following is a series of photomicrographs shoeing some typical structures of these alloys in various states of heat—treatment•

The

revised portion of the nickel—aluminum diagram* Figure 34, (fron 80— 100?£ nickel) based on the results of this investigation is incorporated at this point for reference purposes in connection with the photomi­ crographs*

In general, these photomicrographs depiet three distinct

types of structures —

the single phase solid solution type; the cell-

like eutectic type; the intermediate phase type*

The °C solid type of

alloys showed a typical equiaxed grain structure similar to c>c-brass* It also contained large twins which are likewise characteristic of this type of alloy*

The eutectic-containing alloys possessed two

distinctly different types of micr©structures depending on whether the alloy was of a hypo— or hyper—eutectic composition*

The hyper—

cuteotio alloys (l*e* alloys containing more than the eutectic per­ centage of nickel) possessed the cellular type of structure in which the ©c solid solution phase is surrounded by a network of the NiAl phase in a peculiar oubie pattern*

On the other side of the

or

47

Tablo 6

& M n l t « of Solid Solubility of iluolsuB ia. Siekol

A. S« IK* Data

intiiQlrt« Basalts

Solubility im & • % Ala

Temperature C.

Solubility ia Si-Wgt. % Al.

1360

11«4

1385

11*2

1290

10«4

1500

9.7

1200

8.3

1200

8.0

1100

7.3

1080

6.6

970

5.5

980

6.0

790

5.0

700

5.0

695

5.0

Tamperator* C.

48

Table

6

Hardness liiM w re a s iitc

Weight f Niokel

as east

qusnehsd froa 1100 C

quenehed froa 1S60 C

94,9

B-46

B-45

B—20

91,99

B-81

B-84

B-96

89,0

B-96

B-93

B-96

87,8

B—88

B-87

B—86

84.8

B—93

B-10©

C—28

84.0

B-99

6-24

C—28

81*8

B—35

C— 50

C—41

79.9

m e

C—27

C-30

49

eutectic composition (l,e, the hypo-cutectlc alley*) the Co or Hill phase no longer appeared m

a network surrounding the c*L phase but,

instead* occurred as a massive type of struoture whioh seemed to be extremely hard.

This mas deduced from the faot that these alleys

were very susceptible to relief polishing and the resulting structure exhibited a phase which possessed very steep, sharp, angular sides and extended well above the softer mar hrix, that the

In these alloys it appeared

or Kill phase agglomerated in the solidification process

and therefore appeared as a large, massive constituent instead of as a cell-like network.

In the alloys containing an excess of the

0&

or Kill phase, a needle— like or striated type of structure resulted in the Hill phase when these alloys were quenehed from temperatures above 1000° C,

The appearance of the needle*like structure changed

slightly as the aluminum content increased*

60

Figure 13

94% Viekel alley quenched from 1290° C. Etohed in a Isl mixture of nitric and aeetie acid. 600 X*

t

j Figure Id

99% nickel alley quenohed fron 1100° C« after soaking for 4® hours* Btchad in a 1*1 nixture of nitrie and aeetie acid* 76 X*

51

Flgurs 15 •hows th« ^ p l « a l solid solution typa of s t n e t * ure found la all alloys quenched from any part of the marked solid solution region la Figure 11*

Those alloys are usually character ised

by large* equiaxed grains in which tains frequently occur*

This parti*

cular alloy was quenched fron a temperature of 129©° C* and therefore was entirely within the single phase solid solution region when quenehed* as is evident from, the fact that the photomicrograph shows no secondary phase*

This verified the fact -that the solubility of aluminum in nickel

is greater than G% aluminum at 1290° C*

Figure Id shews a structure similar to that found in Figure 12*

This alloy was likewise quenched from a temperature which placed

the alloy wholly within the single phase solid solution region at the instant of quenching *

The dark spots in the structure are probably

eteh pits rather than a secondary phase since they did not possess the characteristic appearance of this phase as indicated in other alloys*

Inasmuch as no secondary phase appeared in this alloy after

48 hours at temperature it was concluded that the solubility of aluminum in niokel at 1100° C* was greater than 7% aluminum*

Figure 15

92^ nickel alley quenehed from 1299° C« after soaking for 48 hours* Etched in a mixture of 1*1 nitric a^d aeetie a d d * 75: X*

l'

Figure 16

J-j

88% nickel alloy in the "as oast” condition. Etched in Sehrsm's reagent* Dark area are NiAl phase and light areas are solid solution phase. 75 X.

65

Figure 15 shoe* ths occurrence of a aaaoadary phase in aa oC solid solution matrix.

The secondary phase ia this ease is the

(3 or HiAl phase which appears as small globules* slightly grayish in oolor*

Since this structure shews the presence of a phase other

than the solid solution, it was concluded that the limit of the sol* ability of aluminum in nickel at 1200° C* was less than 8% «inni4r»na> In other words* alloys containing 92% niekel at 1200° C* are in the two phase region designated oC plus Cb in the diagrsm in Figure M , The etchant used in this ease was a mixture of lsl nitric and aeetie acid in acetone which only slightly darkens the (3 or NiAl phase while leaving the

solid solution phase uaattacked*

Figure 16 shows the typical cell—like eutectic characteris­ tic of the hyper—eutectic alloys* in an °< solid solution matrix*

It occurs as a dendritic pattern

Alloys of this composition exhibit

a two phase structure over the entire temperature range*

Alloys poss­

essing this type of structure were very difficult to machine, prob­ ably because of the presence of the hard ViAl constituent as a contin­ uous phase

the

solid solution matrix*

photomicrograph sure the

or N1A1 phase*

The dark areas in this The solid solution phase

appears as white areas both in the matrix and as smaller white areas within the eutectic regions.

54

Figure 17

Figure 18

88^ nickel alloy in -the "as cast" condition* Etched in Sehram's reagent* Bark areas are NiAl and light areas are solid solution phase* 1000 X*

88^ nickel alloy quenched from 1560 C. after for 5 hours* Etched in Schram*s reagent. Dark areas are NiAl and the light areas are solid solution phase, 75 X*

55

Figure 17 shows th# same oell«llke euteetie structur6 as was exhibited in the previous figure but at a higher magnification. In this photomicrograph the (3 or NiAl phase is very much in evidence* as a continuous phase surrounding the oc solid solution phase.

This

structure occurred in all the alloys of hyper«»eutectic composition falling within the region designated as oc plus Q> in the diagram in Figure 34*

As the aluminum content of the alloys increases the thiok-

ness of the network phase also becomes wider*

This network pattern*

however* was found to exist only in the hyperweuteetie alloys*

It

was impossible to detect the existence of any structure within the NiAl network although it is believed that some type of structure did exist*

Figure 10 exhibits the same type of structure as was depicted in Figure 16*

The principle difference between the two structures is

that this structure shows a partial agglomeration of the ution phase in the euteetie areas •

solid sol«>

This probably occurred as a result

of extended heating at elevated temperatures or because of incipient fusion since this particular alloy was heated to within 5° C* of the euteotio temperature prior to quenching*

66

Figure 19

89% aiekel alloy quenehed from IS93° C* after soaking for 2 hours* Etched In Sohram's reagent* Dark areas are NiAl, and the light areas are solid solution*75 X*

Figure 20

89% nickel alloy quenehed from 1595® C* after soaking for 2 hours* Btohed in Scfaram*s reagent* The dark areas are V1A1, and the light areas are solid solution* 1000 X*

Figure 19*

This photomierogaph shows the results of quenoh*

ing a hyper*eutec t io alloy from the two phase region labeled oc. plus liquid in the diagram of Figure 54»

Because this alloy was quenehed

from the nuahy region wherein one of the phases is the liquid phase the struoture is indistinct since some of the euteetie areas are begin* n^ng to melt and become a part of the liquid phase*

m

the photami*

orograph the cell*like euteetie areas still retain some semblance of their original pattern although the internal struoture seams to have disappeared*

Figure 20 shows the same structure as that of Figure 19 at a much higher magnification*

In this photomicrograph the complete

obliteration of the internal structure of the eutectio areas is clearly evident •

The liquid phase in these alloys took on a very glassy appear*

anoe after quenching and no internal grain structure was apparent*

68

Figure 21

85^ nickel alloy in the "as cast" condition etched in a mixture of 1 jl nitric and acetic acid in acetone* 75 X*

Figure 22

85% nickel alloy quenched from 970 C* after soaking for 7 days* Etched in Schram*s reagent* Dark areas are NiAl nnH -the light areas are solid solution phase* 75 X*

69

Figure 21 shows the typical struoture found in the "as east" hypo-outeotie alloys*

The eell—like euteotio areas hare been replaced

by large G > or NiAl particles in an a c solid solution matrix*

The

change in the appearance of the euteotio alloys may be due to the fact that on this side of the euteotio point in the diagram of Figure 3& the solidification range is much greater than on the other side of the euteotio point and as a result more opportunity is afforded for the agglomeration of the second phase*

In addition, it is possible that

the excess NiAl constituent -which precipitates first in the solidifica­ tion process on this side of the euteotio aet as nuclei which promote the growth of the large, massive structure*

Figure 22 shows the same type of struoture as that in Figure 21.

The NiAl or Q> phase appears darker in this photomicrograph because

Schram*s reagent was used as the etchant*

Note the presenoe of the

dendritic pattern which still remains oven after prolonged heating at relatively high temperatures*

Figure 23

Figure 24

85% nickel alloy quenched from 1367° C* after soaking for 3 hours* Btched in Sohram*s reagent* Dark areas are NiAl and the light areas are solid solution*

1000X*

84% nickel alloy quenched from 1100° C* after 48 hours

of soaking« Btched in Sohram*s reagent. Dark areas are NiAl and the light areas are solid solution. 1000 X*

61

Figure 23 shews th® oharaotsriatio &oodl9 «llko structure present in the alloys with an excess of the NiAl phase when these alloys are quenched fron elevated temperatures*

These needles are

very similar in appearance to the martens ite needles found in quenched high carbon steel*

This would seem to suggest that there exists in

these alloys some type of phase transformation whioh is suppressed when the alloys are quenched from elevated temperatures •

This parti*

cular type of needle structure appears to be more closely associated with the NiAl phase since it was impossible to find any evidence of its occurrence in the hyper-eutectic alloys*

It is entirely possible

that a similar needle-like struoture is likewise present in the NiAl network which surrounds the X

solid solution phase in these alloys;

however* no such evidence was found in this investigation* Figure 24 shows an enlarged seetion of one of the massive NiAl particles in a hypo—euteetie alloy quenched from a moderately high temperature*

In this photomicrograph the NiAl or (3 constituent

shows some semblance of the needle—like internal struoture whereas the solid solution matrix is absolutely free from this structure* In this particular ease* quenching from a relatively low temperature has permitted the NiAl phase to agglomerate completely into the large massive structure prior to quenching* appearance occurs in the 0

As a result the needle—like

or NiAl phase only and not in the entire

alloy as was shown in the previous photomicrograph*

This gives addi­

tional support to the aforementioned supposition that any phase change which may occur in these alloyB is probably associated with the or the NiAl phases

3

62

Figure 25

84# nickel alloy quenched fron 1567° C* after 3 hours of soaking at temperature* Etched in Sohram*s reagent* 1000 X*

Figure 26

82# nickel alloy iQ the "as oast" condition* Etched in a mixture of 1*1 nitric and acetic acids in acetone* The gray areas are NiAl and the light areas are solid solution* 75 X*

63

Figure 25 shows a struoture similar to that la Figure 23 except that the needle*like structure appears to be finer in this alloy*

Subsequent photomicrographs of these alleys seem to indicate

that as the aluminum eontent is increased* the struoture beoomes finer* Except for this difference* the two structures appear to be quite similar*

Figure 26 shoes the "as east* structure obtained in the alloys containing 81*5?& nickel*

No evidence is found in this micro-structure

of the needle—like pattern which appeared in these alloys when quenehed from, elevated temperatures*

Since this structure was obtained on ex­

tremely slow cooling* no suoh structure would be expected* particularly if the assumption regarding the occurrence of an additional phase change in the NiAl alloys is actually the cause of this suppressed structure* This alloy was etched in a 1*1 mixture of nitric and aoetio acid and as a result the NiAl phase is only slightly darkened*

Figure 27

Same alloy and treatment as in Figure 26* Etehed in Sohram*s reagent* Dark areas are NiAl and the light areas are solid solution* ,75 X*

Figure 28

82%nickel alloy quenched from 1180® C* after soaking for 48 hours* Etched in Sohram’s reagent* Dark areas are NiAl and the light areas are solid solution* 75

Figure 27 ie exactly the same alloy as Figure 26 and shows the effect of differences in the etching characteristics between a ltl sixture of nitric and aeetie acids and Sohram*s reagentj the latter darkens the NiAl phase whereas the nitrio-aoetio acid etch only slightly discolors this phase*

In addition* this photo-micrograph shows a remark­

able similarity between these alloys and the brasses* in the "as east" condition*

Figure 28 shorn the effeots of quenching alloys in the NiAl rich portion of the diagram on the internal structure of this phase* The needle-like or striated structure is definitely visible wherein tha darkened areas which are the NiAl or (3 phase * structure is likewise obtained in the are quenched from the (3 region*

0

»brasses when these alloys

In this ease* the nickel qlley was

quenched from the two phase region designated gram of Figure 3L4L*

This type of

plus

in the dia­

Here again, this striated or needle-like structure

is found to occur only in the NiAl or G> phase*

66

Figure 29

Same alloy as in Figure 28 at 1000 nagnificationa • Etched in Sohram* s reagent* Dark areas are H1.A1 and the light areas are solid solution*

Figure SO

82# nickel alloy quenehed from 1570° C* after soaking for S hours at temperature* Etched in Schram*e reagent* 75 X*

I

67

Figure 29#

This is the s«sa struoture shown in Figure 23

but at a mmeh higher magnification* tion areas in a G* or Sill matrix*

It d e a r l y shows the solid soluw Note the faint striated struoture

within the NiAl phase*

Figure 30 shows the needle-like phase in the 82^ nickel alloys at a rather low magnification*

This struoture bears a remark­

able resemblance to the martensites type of struoture obtained on quenching a high carbon steel*

This alloy was quenehed from 1367°

C. which placed it entirely within the single phase region designated Q> or NiAl in the diagram of Figure 34* was completely homogenous and no dence*

For this reason* the alloy

solid solution phase is in evi­

This offers further evidence that the needle—like struoture

is very closely associated with the NiAl phase*

Figure 31

82JS nickel alloy quenched from 1367° C. after soaking for 3 hours * Etched in Schram rs reagent* 1000 X*

Figure 32

805S niekel alloy quenched from 1100° C* after soaking for 48 hours* Etched in Schram*s reagent* Dark areas are the NiAl phase and the light areas are the solid solution phase* 76 X*

69

Figure SI above the state atraeture pictured in Figure SO but at a each higher eagaifieatioa*

This photomicrograph clearly

indicates the fineness of this needle—like structure end

aakea

evident the similarity between these structures and the nartensitio structures found in quenched steel*

A similar structure was likewise

obtained b y Alexander and Vaughn for atlloys of this nlokel content when quenched from 1395° C*

Figure 32 shows the structure similar to that in Figure 28 indicating the similarity between the structure containing 80% and 82*©£ when quenched from 1100° C*

The same needle-like or striated

type of structure is evident in the H1A1 structure *

lass od. solid

solution phase is present in this structure than in that shown in Figure 28*

This is due of course, to the fact that an increase in

the aluminum content shifts the alloy composition closer to that of the intermediate phase region of the diagram (Figure 3d) wherein the alloy would show a 100% NiAl structure*

Figure 33

8 G% niokel alloy quenched from 1370° C. after soaking for 5 hours* Etched in Schram* s reagent* 75 X*

71

Figure 33 shows a «truetur« in -which, the alloy contains 100# of the HiAl phase*

This alley was quenched from 1570° C** whioh

placed It in the single phase quenching* ing

100^

£6

or H1A1 region at the instant of

As would he expected* this alloy showed structure contain­

of the fine needle-like constituent*

A PORTION

OF THE REVISED

NI-AL DIAGRAM 1950

1500 LIQUID

1400

LIQUID

os

LIQUID

NiAl

1300 OR Os SOLID

1200

SOLUTION

OR N iA l

1100

OS

IOOO

SOLID

SO LU TIO N

900

800 80

90

85 WGT %

NICKEL

Fig. 34

95

IOO

75

DISCUSSION OP RESULTS The results or this work indicate that the portion of the nioke 1 -aluminum equilibrium diagram from 80*100^ nickel la a simple eutectic type of diagram with decreasing solid solubility at each end of the diagram*

For the purposes of this report* this portion of the

diagram from the intermediate oompound composition of 100^

6 8 *8 ^

niokel to

niokel can be considered as a separate diagram by itself*

In

this case the end or terminal points on the diagram will occur at 68»5?& • and IOO56 nickel*

In general* it partially confirmed the work

of Alexander and Vaughn with regard to the c-C solid solution region although it is at variance with their work with regard to the eutectic region and the remainder of the diagram*

In this work no evidence

whatsoever was obtained to confirm the existence of a 8

or NisAl

resulting from a peritectic decomposition as stated by these authors* Peculiarly enough though* the thermal arrests obtained by them agreed very closely with the arrests obtained in this investigation.

However*

unlike the work of Alexander and Vaughn, the results of the thermal analysis and the microscopic examination in this investigation checked to within

5® 0

. with regard to the determination of the eutectic temp*

erature*

The solid solubility determinations checked very closely to

the results of Alexander and Vaughn* Tri the micr os copie studies* one peculiar phenomena which was encountered and which originally seemed quite puzsling was the rather abrupt change which occurred in the appearance of the NiAl phase in the alloys on the (5 or the NiAl rioh side of the eutectic composition.

The cellular type of structure so characteristic of

the hyper—euteotio alloys suddenly became massive in appearance in

74

■the hypo-eutectic ftlloyi«

This aay 1m

a ocnplloated phsnonsna Iiito It *

ifiE s w f w j ® s n sr g iM ox* surfaco ta&isiou or it nay /bo duo to a much more aimplo jdio&onsaa such, as a diffarenoa in the solidification range on each side of -the eutectic point*

If the latter explanation is

correct* then this oould conceivably account for the change in appear"* once of the Sill phase since a wider solidification range would pro— vide more time for the agglomeration of this phase*

It may also be

due to the fact that in the hypo—eutectic alleys the presence of an excess of the NiAl phase may act as a triggering or nucleating mechanism whioh promotes the growth of this phase in the form of large* massive particles*

Actually* it is probably a combination of both of these

mechanisms*

The extremely wide solidification range on the NiAl rich

side of the eutectic composition proves sufficient time for the agglo­ meration of the NiAl phase whieh is present as an excess constituent and oan therefore act as centers of mucleation thereby promoting the growth of this phase in the form of large massive structures* The hardness measurements taken on the various alloys both in the *as oast** end in the heat treated condition agreed very well with the readings reported by Alexander and Vaughn*

It was quite

unexpected however* to find such a significant- increase in the hard­ ness of the NiAl alloys when quenched from elevated temperatures. This increase in hardness was probably due to two effects*

In the

first place these alloys exhibited a decreasing solid solubility with decreasing temperatures and this of course could account for the in— , crease in hardness because of the entrappment in the NiAl lattice of seme of the oc solid solution phase*

The increase in hardness could

also be due to the development of internal stresses resulting from

75

the severe quenching, although it is doubtful that such sue increase in hardness m s

due only to quenching stresses*

It seems quite just*

triable, at any rate, to assume that this increase in hardness is in some may associated with a highly stressed crystal lattice and particularly so in view of tie fact that the resulting structures exhibited the fine, needle—like appearance, characteristic of the . highly stressed martensitio structure in quenohed, high carbon steel* Another more plausible explanation of this marked increase in hardness is the possibility of the existence of an order—disorder relationship in the O

or NiAl phase*

Suoh a relationship mas reported for the NiAl

phase by A* Taylor (6 ) (14)*

Structures similar to those shown in

Figures 28 and 32 have also been obtained in the Q

brasses by quench*

/

ing from the (^> region.

In this system the existence of the ordered*

disordered relationship has been definitely established in spite of the speed with which the transformation proceeds.

Because of the

similarity of these two systems the need for further investigation in this region of the diagram is apparent. The results of the experiments on the age*hardening eharae* teristics of the niokel* aluminum alloys mere moderately successful, Shoreases in hardness of the order of 25^ mere obtained in alloys containing 9296 niokel

8% aluminum*

One disadvantage of these

alloys from the standpoint of industrial application is the fact that prolonged soaking periods are necessary at temperatures above

1000°

C* in order to insure the complete solution of the secondary phase. It mould seem, in view of the fact that these alloys possess other desirable properties, that other experiments are in order to determine the possibility of enhancing the precipitation hardening characteristics

76

of those alloys b y the addition of various other elements*

CONCLUSIONS 1

*

Tha portion of the nioke1 —aluminum equilibrium diagram

from 80-100^ niokel is a eutectic type of diagram with decreasing solid solubility at eaeh of the terminal points* (Reference, Figure 34), 2•

No periteetio reaetion was found to oeeur at 1395° C#

as reported by Alexander and Vaughn* 3*

The euteetie temperature of these alloys was determined

to be 1365° C* rather than 1385° C* as reported by the same authors* 4*

The K. solid solution alloys showed a maximum solid

solubility of 10*5^ aluminum at 1563° C* and a solubility at room temperature of 5% aluminum* 5*

The maximum solubility limit of the oc solid solution

phase in the ohifr-cm at 80° C.

p*

= 5560

I 2*11 x 10

jJ 9600 x 1

p

— *053

cm

Calculation of optimal radial "thickness •

r0 ^ 2*22 p

Ta s 11*54 if 9600

or

ro - 11*54 Ct

Actual radial thickness* r

- thickness of copper tubing

r

- *050* x 2*54

r * *0762

om

Height or diameter of a single ooil h =■ *25" x 2*54 h

*635

om

Index ratio of ooil conductor,

A =

&-**■6-

A

x *0762 ,053

-

A

-

2.03

Resistance function for coil* K r - (sinh/y—sin/Q (cosh /\-cos/\) - (sinh 2*03 - sin 2.03) (Cosh 2*03 • cos 2*03} Ky.^ 1*07 Inside radius of ooil* b c assumed to be 8,89 cm. Effective inner radius of the ooil b* «.

+- p

^

b» —

b* 1*

os

= assumed -bo be

11*4

«™t

Number of turns of the ooil* N

n*

— 8*93

Length of ooil oTer burns• 1

m.

8*89 +- .063

—

8

Space factor* s =

n

s -

8

TT h 4 x 1 x 5.1417 x ,635 4 x 11*4

s o.

*35

Correetion factor

K*

is function of 2b* 2 b* Kx

or

from. p* 72* N* R* Stans el

K x = *585 p«

Referenoe dimension of the charge# p

p q*

2 2 x 8*95 11*4

-

3580 if #005 f 9600

•= #600 cm

Radius of the charge* a ~ 5*7 cm*

1«

T#

r.

Length of charge. 1* —

s•

17.8

om

Ratio of h/a* b/a =.

b/a t.

8

#89 5.7

- 1*56

Index ratio for the charge.

/\=-

rr xt Pa.

* - \2

x *635 .600

A £ u.

Resistance function for the charge M ^ - is a function of the index ratio and is obtained from N. R. Stansel p. 35 M ^ - 1.21

Sr* Ratio of l*/2 a l»/2a ^

17.8 2 x 5.7

lj6 a — 1.56 w.

Correction factors from graphs on pages 73 and 74 of Stansel *

*68

Y*. * .56

▼la

Q

Stannary of data

data

0

x*

Charge data

.053

= .600

**.

^ •118

a

r

= .0762

1* - 17.8

h

- .635

b/a ^ 1.56

A

- 2.03

Ur

1.07 b

&

- 8.89

= 5.7

1.21

= .70

Fr ^ .707

b * - 8.94

t

= .635

N

8

k

- .167

.35

T r ; .58

a

^ - -

**

* .585

.45

Resistance of the primary circuit t

=. 1*83 l/T i

r

1#85

iT~

H x

b*

K

10

* l9 6 0° x 64 x 8,94 x 1.07 11.4 x .581 x 10 *

r. ^ .0165 4Resistanoe of the secondary circuit -

4 77"Vf" /^Qsx 10 ^ x N 1

r 4 77~V96QQ

r M — .214

* x

10

x a x M

^

|/»005 x 10 x 64 x 5.7 x 1.21 25.4 x 10 ^

▼ii.

Eswtaiiet of the primary oirooit *x_r

8

■3 77 f

x. M

r n

*— b

p

Kx

—

..3 * 4 -=

8

*7 9600 x 64 x 8,94 x .585 11.4 x 10 ^

-070 Reaotaaoa of tha secondary circuit

-3 77

f IT a 1x10^

Y„ -j- r

^

YK

3

//

9600 x 64 x 5.7 x .55 ^ .258 x . 7 0 x .585 25*4 x 10 .707 x .08

X^-

-8

x^-

.236 -2 —

Total resistance of the circuit R R

Tc^y r^,

~ .231 JT—

Total reactance of the circuit X =- x«oX

— .306

The impedance of the circuit Z= {r Where

— X*"

R-

X -=-

C

5.1471

for pure capacitauioe

1 2

- .383 -^7—

TTf c

Therefore a. *_ Z “ X -_____1_______ 4 TT^f v C ^

▼ill#

c =■

1

4"ti'w

t W*-

1

i'-nSc C96oo) (.1471)

C — 24.6 -