Thermodynamic properties of liquid CuSnZn alloys

Journal of Alloys and Com~xmds 247

: lW7 I IXS-IX9

Thermodynamic properties of liquid Cu-Sn-Zn

alloys

Ming Peng, Adolf Mikula*

Abstract Using an appropriategalvanic cell. the partial free energies of lint in liquid Cu-Sn-Zn alloys were deremuned ins a function of propcnies were obtained liar 40 alloys. Their composition was situated WI four and temperttture. Thermodynamic cross-sectionswith constantratios Cu:Sn of I :3. I:?. I :I and 2: I. Th’ L mtegralfree energy and the intcgnl cnthalpyfor the remary system ill 1023 K were calculated by Gihhs-Duhem integration. concentration

1. Introduction

polished with a tine emery paper and zinc was cleaned

Owing to health concerns and environmental reasons. lead will be replaced in the near future in all solder materials. New lead-free solders must be developed. and for certain applications the ternary X-Sn-Zn alloys could be candidates. We have already investigated the Ag-SnZn [II and Au-Sn-Zn 121 systems. Since copper alloys have excellent electrical properties and high corrosion

prior to its use by melting under vacuum and filtering through quartz wool under a purified argon atmosphere. Copper was used without further puritication. The metals were weighed and sealed in silica capsules under vacuum and melted together at 1300 K tar several days. After heat treatment the alloys were quenched in ice 3 g of each alloy composition water and approximately was used for the e.m.f. measurements.

resistance, they are important materials for different industrial applications. However. data of thermodynamic properties and of the phase diagram are scarce for ternary copper alloys. Thermodynamic data are also needed for the calculation of phase diagrams and for the improvement of industrial processes. In the present investigation the thermodynamic properties of zinc were measured with an e.m.f. method at four cross-sections with a constant Cu:Sn molar ratio of 21. I: I. I:2 and l:3. A Gibbs-Duhem integration was applied to determine the integral thermodynamic properties for the whole ternary system. From the discontinuities in the slope of the e.m.f. versus temperature curves the liquidus temperature for most alloys was determined.

As electrolyte. the euteetic mixture KCI-LiCI with addition of 0.5 ntoF& ZnClz was used. The preparation of the electrolyte and the assembly of the e.m.f. cell are described by Geffken et al. 131. Measurements were carried out on heating and cooling. The heating and cooling rate was 8 to 10 K h-l. Every 50 degrees the temperature was kept constant for a longer period of time to check the stability of the e.m.f. The temperature range of measurements was from the liquidus up to II00 K. The following atrangement for the experiment was used: Zn(l)/Zn

_’(KCI-LiCI)(I)/Cu-Sn-Zn

alloy(l)

Under reversible conditions, the Gibbs free energy change for the reaction is given by

2. Experimental procedure

AC,,

The ternary alloys were prepared from high purity metals (4 N copper from Fischer Scientific Co., NJ; 5 N tin

where F is the Faraday constant (96 486 C mol-‘), E the electromotive force of the cell, R theuniversal gas constant (8.31434J mole’ K-l). T the absolute temperature and a,, the thermodynamic activity of zinc in the ternary alloy, with pure liquid zinc constituent as reference state. At all four cross-sections the e.m.f. versus temperature curves

and zinc from Johnson Matthey GmbH, Vienna,). In order to remove the oxide layer from the surface, Sn was ‘Conespading

author.

0925~8388/97/$17.00 0 1997 Elwier PI/ SO925-8388(96)02575-3

Science S.A. All rights reserved

= - 2FE = RT In (I~”

(1)

This system was evaluated by Hultgren et al. E(mV

) = ,I + h/i K)

(1)

For cxh expsrimrnr two cooling curves were recordrd. The ;pwment hrtwern these two curves was wry good. The drvkuion of the measured r.m.f. values from the tittrd one> \\;a\ ::.0.7 mV ;u 5 and IO at.% Zn. between 50. I and 20. IS IT’S.at ali other compositions. Using the measured values of E. Ihe (I,,, and AC?,,, at a temprramre were calculated. From the temperature drpcndence of E. the partial molar entropy As,,, and were derived. using the following equarnthalpy Xi,,, tions: given

as,,, = ‘FIXlilT)\,,.

= 2hF

(3)

thermodynamic Spencer I I7 I.

re-evaluation

Some information

is given

on this ternary

- El = G,,,

+ 7Is,,,

= - 2oF

The man

(4)

kihhs-Duhem 141 (eq.

(12)

equnrion

given

their

publication)

in

by Elliott

system is given by

l’ahle I Measured e.w.f. datn a,.‘% %n

E m.T.

was

the integral thermodynamic quantities whole ternary system from the e.m.f. data.

- I4.wJ0 + 0. I xixwi K, - 12.MN,+O.l INiT - ,2,1X0+0,077’,27(K, ~~IO.IXOIO.OMW17iK)

7xs xos X6.3 WJ.3 P I ‘J

-Y.?73+0.0,47lXT(K~ --X.-EL) +O.O35477I K,

10

SY.YY

- Y.07’) + U,U?X’JYT( K ,

XX.3

for the

70.00

mX.2X.l t0.023127’~K1

xx0

79.Y’J

-4.Sh.l f 0.013YOTl

~JU.01

-Oh’)3 + U.UUSYhT~ K)

applied

determine

S.“l lO.Ul I’,.‘,‘~ 3U.Ul 3Y,OCJ -l’J.Y’J

and Chip-

KI

Yl7

X43 __

/hJ (‘rr:91 I:2 ~.n~.~.~-s~,~.rirat

3. Experimental results and discussion The thermodynamic data of the three binary were taken from the literature.

systems

4YY

.5.74X+ 0. I24XhTt K)

7YU

Y.YY

3.X66 + U.UY.3I I T( K ,

X3

?OSX,

0.X04+ O.OhXOITI K I

x7x

?Y.Y’J

‘)I2

40.01

- 2.643 + U.OS4YW K , - 3.397 t-O.0429 I T( K,

SU.Un

-4.37h~U.U34SY7~K~

Y.uJ

M,.OO 7U.W X0.w~

- S.663 + O.O?7-!7T~K, - 4.467 +U.O1Y.?3% K, 3.Y31 ?U.U132hTtK)

Y?3 XXS X30

II.729 + O.UUSI47i K ,

X33

X’J.‘r)

In

this

system

the

thermodynamic

properties

were

investigated with an e.m.f. method from Ref. 151. with calorimetric measurements from Ref. 161. and by a vapour pressure method [7,81. The thermodynamic activities were determinrd with a thermal analysis by ltagaki and Yazawa 191 and a torque effusion method [ IO.1 I!. A review of this binary system is given by Moser et al. 112).

,I’,(‘r,:.slI I:I ,~n,rr-s,~~rbln SSNl ??.h70 + 0. I?OlhTf I0.01 1o.UU 3U.OU .w.tn, 10.01 h0.w

K,

Y33

2 I. I X0 + O.UXX747IK ) I4.2YO+U.Of,W?i-(K~

x73 x72 YU3

Il.3.W~O.WXlST~K) h.hY? + O.U3XYST( K, 3.IUY+O.U313XT(K~

Y44 ‘JS2 Y77

K)

Y43

h’J.YY

-I,.? I h i- 0.01 XJOT( K,

YOS

XO.OU YU.UU

-0.410 10.01 Il7T(lo -0.363 + U.W.,XS71 K,

x3x 7YU

I .X4X + 0.023SYTi

(cl) Cit:9~ 2;/ c-,r,r.,-.,cr,ri,,rl

A new and very extensive review of the Cu-Sn system is given by Saunders and Miodownik [ 131. E.m.f. measurements using a solid electrolyte were carried out by Sommer et al. I I41 in the copper-rich solid solution region of this system. New calorimetric investigations of liquid Cu-Sn alloys are reported by Lee et al. 1151. Their data of the mixing enthalpy of liquid Cu-Sn alloys at 997 K are a little more negative than the values recommended by Saunders and Miodownik 1131 and by Hultgren et al. [ 161.

a

and

Tefelske et al. [ 181. We started our investigation from the binary Cu-Sn system by adding zinc. The activity of Zn was measured along four cross-sections with a constant Cu:Sn ratio of

tcrl Ce:.G I:.? w,rr-.wcrhm

AI?,,, = 2F[T(Xlil7),,,.

[ 161 and

by Kowalski

5.01

JXX)o+

0.

I IYhYTt K b

012

IO.01 ?O.UU 30.01

3Y.4YO +O.OXYIS7’( KJ 3?.3UU+U.USYXl7IK,

xxs YU3

272YO+ U.O4I 2X7’(K)

9.5.5

40.0 I

??.47O+U.O3013T( K)

973

SO.02 ha00 7U.UU

I3.970+0.0?533T( K) 6.432 + 0.02 I37T( K ,

9x7 Yw 960

x0.M) ‘H).(w)

I.2?h+lJ.OII?WK, 0. I79 -f U.UWiDT~K,

4.Yl7.0.014lOT(K~

YO? X?I

M. PW,~.

2:l.

I:I.

I:2

tnd

13.

At

A. Mi!.rh

I ,O,‘“,‘,,

0, Allor\

each fixed composition the

temperttture versus e.m.f. curves were straight lines and the e.m.f. is expressed by Eq. (2). In Table I(a) and (b) the parameters (I and h are given for all measured alloys. The activity of Zn in the Cu-Zn system

shows

the Cu:Sn

a negative

2:I

and at Cu:Sn

I:I

content

activity

the

deviation

cross-section it is only of

from

Raouh’s

the deviation slightly zinc

is

negative.

becomes

law.

less

At tin

tl,,,

l&S-

189

IX7

the partial Gibbs free energy. partial enthalpies and pnrtinl entropies are listed. The integral Gibbs free energy ttnd the enthtlpy of mixing for the ternary Cu-Sn-Zn system were cttlculttted using an equation given by Elliott and Chipman 141. The

the

and more

, IW7,

of zinc.

to Sn

positive. The results of our inve+gtion in the ternary system are presented in Fig. I. and in Table 2 the activitie\

.‘I,,

c,m,p
integration

negative

At a higher

more

‘rnd

were

ratio.

value>

with carried and for of

out along

the

Hultqcn

the line

integration et al.

[ 161

of tt constant

constant crlcuktted

used.

The tesults are given in Table 3 and the k-Gibbs free energy curves for Abe ternary system ttre plotted in Fig. 2.

t

AH,,tJ nwl ,

?-MS? IY4S7 I1032 ,,“KS 755 1 i7,,

271’) 243 I 1.150 IY&l 17x’) ,617

?6.1115 11.397 IS.037 I I .7SY Y. 10s h.X-15

A<;,,,IJ nwl

AS,,,11 K

Id) Cu:.G /:.I mnl I:.? uo~~-wc~rion~ ~4, lO2.i ti Cu:Sn 13 0.0s,K) O.lWl O.IYY+ 0.3001

0.0549

0.39YY

0.1015 0.2lhO ,1.3062 Il.4 I ?X

O.JY99

o.s21 S

wiYYY ,~.7wO

O.h170

iY7 I

1751

5.sM

0.7057

2YhS

ISW

4.461

O.7YY9

0.x033

iXh3

XXI

2.hXZ

O.wOI Cu:Sn

O.XY? I

Y7l

IW

I .0x0

I:2

O.,MW O.(r)99

O.,l.M 0. I055

O.?wl O.?YW 0.4OOl

0.3WO

-7XIS

0.5nlxl O.MXM 0.7Ow

O..lY4X ,l.M)lO

SYXS ~J.13,

6Sh X-u IOY3

X.2X0 h.675 S.302

0.70x2

- 1Y3S

Xh?

O.XOOO

OX036

- IX6u -x73

7SY 141

3.71 I Z.SM) O.WI

(6, CI~:SII Cu:Sn

?S7SX IYIZX

IIOY - 746

xOY4 17.%X

0.2026

I3SXI

. ISS

13.123

O.?YhY

I,l3?X

510

o.YO2-l

0.x999 I: I d

?:I

~~rr~,~.s-sc~~lif~~ts or /K.i

l,mAl

K

I:I

O.OSoO 0.1001

O.O3hd lw7XY

2XOYh -21605

O.?OOO U.3OOl)

0. IS62 02.523

-1S7Yl -11713

0.4,lOo 0..5001 0.6lMO

0.3479 OMYY 0.5546

XYXI -67Y-I -5014

-I1Y1 -600 - 357

0.69YY

0.6557

- 3SW

42

ISSO

O.UwO 0.9QOU cusn ?:I 0.050 I O.IOOI

0.7796 0.9Ow

-1IIX -XXX

x7 7”

?.lSS 0.936

-437s -40x7 -27.5x ‘IXX

23. I xx 17.124 I2.7.w 9.310 -- .

7.Sl7 6.0.5s 4..5=1

0.0240 O.OSlh

-31733 -x20

-810s -7620

?3.097 17.203

O.ZOOO 0.3001

O.llW 0.2066

- IX041 - 13414

-6233 -5266

I I .SJZ

0.4001

0.2985

- IO2X.1

-4326

5.813

0.5OCNl 0.6ooo

0.4046 0.5263

-76% -- 5459

-26% - 1241

J.XXX

0.7Oal

0.6447

- 3733

-949

2.722

0.8000

0.7499

-2448

-237

0.9OlM

0.11893

2.16?. 1.009

-998

Cu

C”” h,n*r) cu.S” for IO23 K

7.%5

35

4.123

’ mol ‘,

Table 3. Continued at.% Zn

c,< CI! , .: 0 (HI

(01

.Z/,(~

-S627

-696

4.x20

--414

3.632

> ! -0 n--

I(H)

7.x9-l X.7?)

YSSNJ

-2363

-IX

2. I x4

2.5 110

v-s,?;

.‘I’_‘.‘h

.5z 17x

‘).3(H) ‘J.hYS Y.Y71 10.146

.3’,K1

vsi,

2x7 -10.3 !i25

.:i InI 41 IHI

‘No:

h39

10.2I

Vhh2

4s I”1

v-127

731 7Y9

10. 60 Y.YYS

x.57

9.737

922

9.40s

I IN,2 IOX II4l IOhX 9.50

Y.01 I x.543 7.97 7.253 h.367 5.312

x27

J.OYO

646

2.s70

- h?X -.5X3

7.407 !L%+l 9.212 9.622 9.887

-Vl,Ll

XhYlJ -~x?ls -7h52 -70,

i.c.lXI x0.w 85.W ‘HI(HI

I -62X0 - 9-M -44x5 ‘-33.57

L)S.l,l,

-- IYX3

0.W 5.,x, IO.OU

I:.?

I

AS ,,,, (J K

-4130

L,::i

ihI cl,:slI

‘)

X.5.00

40 : ,

hO MI hi.lXf 70 (H,

(Jmol

90.00

,i,)o

?i.lM)

LH.,,.

h.S?-l

20 InI

iI,,“,

‘)

I-L-l

,.:

IIIIYI

,,,,. (Jm~l

(,.\.N

\<.:..~~.

s IWI

X


,143

I

I

I

IS.00 2”SW)

- IO.527 - 10773

-693 -683 -659

XX,

-IOXYI

-61X

IO.041

30.00

- IOXYY

- 560

IG.iiK,

3s.w

- loxlIx

J0.W

- IOh

-484 - 397

I0.091 9.998

JS.lXl

- 10353

-301

9.826

SO.(X, 55.Ol, hO.Ol,

- YY9S - YSSO -YO,s

-201 -97

9374 9.240

II

x.x23

6.Wl,

-x3x7

I26

X.321

70.00 75.Ou

-- 7h62 --.

24s 3.59

7.721) 7.030

4s3

6.1Y7

496 454 293

5.185 3.927 2.321

X0.00 XSSX, 9o.W

x33 -%X8 -1XlY~ -.x5&l

9s.w

--208,

(‘I) C,r:Su 2:/

<‘NLW.

0.00 5.00 10.00

scvri0n 0, IO?.? K -l(r)41 - 12415 - I32.w

- 36.52 -3x75 - 40x0

7.124 8.34X X.9.54

-4234 --J.sl3

9.331

2.5.00

1427s

-‘Ml?

9.640

30.00

- 14290

-444s

9.62 I

3S.00 40.00

-I-l170 - I3924 - 13558

-4436

9.514

-4365 -4220

Y.344 9.127

ho.00

- I3074 - 12472 -1,752

-3999 -3704 -33.51

X.87 I 8.571 X.212

64.(K)

- 137x0 -14113

IS.00 20.00

45.M) so.00 ss.slLl

‘)

9550

- 10910

-295x

7.773

70.00

-9940

7.5.00 X0.00

-8X34 -7578

- 2540 -2103 -1643

6579 S.802

x5.00 90.w 95.thl

-61.52 -4517 -2.591

-1I.V

4.xX8

-640 --IX3

’ mol

7.234

3.79 I x.54

The minimum is at approximately 48 at.% Cu. 24 at.% Sn and 28 at.% Zn. The data for the binaries Cu-Zn were taken from Gerling and Predel (191 and for Sn-Zn from Moser and Gasior 151. A similar procedure was used to calculate the integral enthalpy of mixing. In this case the data, given by Hultgren et al. [ 161 at 1400 K, were used for the integration constant. The results for the enthalpy are presented in Fig. 3 and given in Table 3. AH,,,i, is negative at the Cu:Sn 2: I and I: I cross-sections. For the I :2 and I :3 cmss-

I‘ ) Cu-.Su 1.1 r m.u rruiw,,t (11 IO?.3 R OSX, s.00 l0.W 15.W)

20.02 2s.w

10233 -llSSX - 122.77 - ,x65,

-I?YlY

-197.5

8.072

-2141

9.20s

-2245 -2327 - 2.384

9.767 IO.099 10.2x4

-13007 - 12984

-2406

10.363

30.00 3s.Ou

-I2844

-2393 -2350

10.353 IO.257

40.00

- I2SY3

-2283

10.079

45.00 50.00 SS.(X,

- 12238 -11785 -1,236

-2193 -2080 -1940

9.819 9.487 9.087

60.00 65.0”

- 10593 -9x52

7osul

-9003

- 1773 -1584 -1380

I?.622 X.082 7.452

75.00

-

-1167

6.710

Fig. 1. Activity uz” of zinc with Pure liquid zinc a a reference state for

-943

5.838

four Cu:Sn cross-sections 2~1. I:I. I:2 and I:3 at 1023 K and for the binary Sn-Zn (Hultgrenet al. [I61 at 750 K) and Cu-Zn (Ceding and Predel 1191 at ll73K).

x0.00

8032 -6915

0.0

0.2

0.4

0.6

0.8

1x9

CU

04

0.2

0.6

%”

08

srl

Acknowledgments Financial support for this investigation was given by the Fondn %ur FGrderung der wissenschaftlichen Forschung under Grant No. P 0!9102-CHE.

121S. Karlhuhw. K.L. Komarek atd A. Mikuh. Z. Mrrdlkd.. 85 (1994) 307.

-5 -

131 R. GefRm.

K.L. Komarek and E. Milkr.

Trwrs. NM&

239 ll%7)

1111. 141 J.F. Elhott and J. Chipman. 1. Am. Chrm. SK.. ISI 2. Mow

and W. G&+x.

161 G.J. Kkppa. 1. Phw

7.3 t 1951) 2a2.

Bd/. Acud. Pd. .%i.. .7/ (1983) 19.

Chum.. 59 (1955) 355.

171 E. Schal and F. Wolf. Z. Mrru//N 50 (19.591 20. 181 E. Scheil and D. Miiller. Z. Mevall~d., 5.7 389.

t I%Z)

191 K. Itagaki and A. Yazawa. Trims. 1. /nsr. Mel.. 18 t 1977) 825.

sectionsthe mixing enthalpyexhibits a changeof sign. The integral enthalpyof mixing for the whole ternary systemis plotted in Fig. 4. For the Cu-Zn system the data of

[IO\ M. Lathrop. Y.A. Chug

Parameswaran and Healy 1201 at 1400 K were used and the values of Hultgren et al. 1161 at 750 K for the Sn-Zn system. Since no data about the liquidus were found in the literature, Table I gives the liquidus temperature for most alloys which was taken from the distinctbreak in the e.m.f. versus temperature curves at the liquidus. The accuracy was estimated to be +7 K. The investigation of the ternary Cu-Sn-Zn system yields a consistent set of thermodynamic data of the liquid alloys, which are useful for the calculation of the ternary phase diagram. The data might also help to improve some

[I?] Z.

industrial processes.

1201 K. Pammeswamn and G. Hedy. Mefd.

and T. Tefelske. Mowrsh.

Chum.. 10.3

(1972) 551. I I I I Y.A. Chang. G.C. Wilhelm. M. Lahmp and L. Gyuk. Arm hfw~ll.. IV(IY71)795. Mow. J. Dulkkwicr. ‘k,qr.. 6 1985) 330.

[IJl

t

F. Sommer. W. Balb;rh (1979) 119.

W. Gaiw

and J. Salava. Bull. Alloy Phase

and B. Pm&l.

Thenwhim.

Arm.

.i.Z

[I51

J.J. Lee. B.J. Kim md W.S. Min. J. A/& Camp.. _mZ (1993) 237. 1161R. Hultgren,RD. Dcwi. D.T. Hawkins. M. Gkiser and K.K. Kelky. Sulwwl

Vulws of the Thwm&tamic

ASM. Metals F’d,

[I71

Properlies #f Liinq

M. Knwalrki and PJ. Spnrer.

J. Phase .&pail.. H ( 1993) 432.

1181 T. Tefelske. Y.A. Chang and R.E. Miller. 2985.

[I91

Allow.

OH. 1973.

U. Ceding and B. PI&I.

Metd.

Trans.. 3 (1972)

Z. Mewrllkd. 71 t 1980) 629. Trans. B. 9 (1978) 657.