K I N E T I C S O F N I C K E L A N D N I C K E L S T A N N I D E

S O L U T I O N I N L I Q U I D T I N

G . A . P r i b y t k o v a n d V . I . I t i n UDC 669.71

The r o t a t i n g d i s c m e t h o d is u s e d to s tudy the s o l u t i o n k i n e t i c s of n i c k e l and n i cke l s t a n n i d e s in l iqu id t in in the t e m p e r a t u r e r a n g e 300-700~ S a t u r a t i o n c o n c e n t r a t i o n s , so lu t ion r a t e constants.~ and the n i cke l d i f fus ion c o e f f i c i e n t in l iqu id t in a r e d e t e r m i n e d . It is e s t a b l i s h e d tha t up to Re = 20,000 the n i c k e l s t a n n i d e so lu t ion p r o c e s s is l i m i t e d by d i f fus ion .

In the p r o c e s s of c r e a t i n g p r o t e c t i v e c o a t i n g s o r coa t ings with s p e c i a l p h y s i c a l p r o p e r t i e s on m e t a l l i c m a t e r i a l by i m m e r s i o n in a m e l t , i t is n e c e s s a r y to s tudy the m e c h a n i s m and k i n e t i c s of i n t e r a c t i o n be tween m e t a l s and a l l o y s to be c o a t e d and the m e l t e d so lu t ion . Of s p e c i a l i n t e r e s t a r e s y s t e m s in which a t the m e t a l A - m e l t B b o u n d a r y , f o r m a t i o n of i n t e r m e t a l l i d e s is p o s s i b l e . Since in this c a s e t h e r e o c c u r s i m u l - t a n e o u s l y g rowth and so lu t i on of an i n t e r m e t a l l i d e i n t e r l a y e r , i t i s n e c e s s a r y to s tudy the i n t e r a c t i o n of the i n t e r m e t a l l i d e with the l iquid m e t a l s in p u r e f o r m . At the p r e s e n t t ime s e v e r a l s t ud i e s have been p e r - f o r m e d on so lu t i on k i n e t i c s of i n t e r m e t a l l i d e s in a l iquid componen t , f r o m which i t fo l lows that the so lu t i on r a t e c o n s t a n t s fo r i n t e r m e t a l l i d e s and the c o r r e s p o n d i n g pu re m e t a l s a r e equa l [1-3].

The p r e s e n t s tudy w i l l e x a m i n e the k i n e t i c s of so lu t i on of n i cke l and the compounds Ni3Sn and Ni3Sn 2 in l iquid t in. The cho ice of t h e s e m a t e r i a l s was b a s e d on p r a c t i c a l c o n s i d e r a t i o n s . An a t t e m p t has been m a d e to u se i n t e r m e t a l l i d e s of the n i c k e l - t in s y s t e m a s p r o t e c t i v e coa t ings on n i cke l [4]. M e t a s t a b l e compounds of n i cke l with t in a r e u sed as a d i f fus ion b a r r i e r in s o l d e r i n g of p r i n t i n g p l a t e s [5].

The k i n e t i c s of n i cke l so lu t ion in t in have not b e e n s t u d i e d p r e v i o u s l y , u n l e s s [6] is c o n s i d e r e d . The r e s u l t s ob ta ined t h e r e i n a r e i n c o m p l e t e and u n r e l i a b l e , s i n c e the e x p e r i m e n t s w e r e p e r f o r m e d with m a t e - r i a l s of t e c h n i c a l p u r i t y and with the use of f lux.

EXPERIMENTAL METHOD

The experimental study of the kinetics of solution of nickel and its intermetaUides in tin used the equally accessible surface method and was conducted in special apparatus in a vacuum of (2-5) �9 10 -5 mm Hg [7]. Temperature was maintained within the limits of •176

The nickel specimens, 17 mm in diameter, were obtained by turning bars formed by vacuum re- melting and forging of type HIV anode nickel. The solvent used was type OVCh- 000 tin. No oxide film was observed visually on the melt surface. The iutermetallides Ni3Sn and Ni3Sn 2 were prepared from the same materials in argon in Alundum crucibles, then powdered and remelted in quartz vessels in a vacuum of 10 -4 mm Hg. From the bars thus obtained specimens 8-10 mm in diameter and 5-8 mm tall were cut. All specimens (including the nickel ones) were annealed for 3 h at 800~ in vacuum. Directly before the experiment the specimen surface was polished with fine abrasive cloth (nickel specimens were also electro- polished) and rinsed with ethanol or acetone. The lateral surface was protected from the tin by graphite tubes.

Solution rate constants K were calculated with Eq. (2), obtained on the basis of the Shchukarev- Nernst equation (1)

C = C s ( 1 - - e - X S t ) , (1)

V. D. Kuzne t sov S i b e r i a n P h y s i e o t e c h n i c a l Ins t i tu t e , T o m s k Sta te U n i v e r s i t y . T r a n s l a t e d f r o m I z v e s t i y a V y s s h i k h Uchebnykh Z a v e d e n i i , F i z i k a , No. 9, pp. 100-105, S e p t e m b e r , 1975. O r i g i n a l a r t i c l e s u b m i t t e d M a r c h 5, 1975.

�9 76 Plenum Publishing Corporation, 22 7 West 17th Street, New York, N. Y. 10011. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission of the publisher. A copy of this article is available from the publisher for $J5.00.

1299

d 4

o

z n

r g..qo "I~0 t, m i a

Fig . 1. N icke l c o n c e n t r a t i o n in l iquid t in v e r s u s so lu t i on t i m e (S/V = 0 .1545- 0.1518, w = 16 s e c -~, Re = 1670). 1) 300~ 2) 400~ 3) 500~ 4) 600~ 5) 700~

r~

~00

4oo

~,oo

5,00 i

4

\ I',, i J

1,200

\ /,400 t,600 t, aoo

Fig . 2. S a t u r a t i o n c o n c e n t r a t i o n v e r - sus t e m p e r a t u r e fo r n i cke l in l iqu id t in .

In Cs - - Co I< = C s - - C

st/v

H e r e C s is the s a t u r a t i o n c o n c e n t r a t i o n a t e x p e r i m e n t a l t e m p e r a t u r e ; S, a r e a of d i s c s u r f a c e ; vo lume of m e l t ; C 0, i n i t i a l n i c k e l c o n c e n t r a t i o n in m e l t ; C, c o n c e n t r a t i o n in m e l t a t t i m e t.

D e n s i t i e s of l iqu id t in 0Sn and n i c k e l PNi w e r e taken f r o m [11]. c a l c u l a t e d f r o m the f o r m u l a

(2)

V,

Density of t in-nickel solutions was

Psn-m = Psn" Cs, @ t~N~- Cm. (3)

In a l l e x p e r i m e n t s the n i cke l c o n c e n t r a t i o n in the m e l t was d e t e r m i n e d f r o m the l o s s in s p e c i m e n weight (tin was r e m o v e d by e t ch ing in h y d r o c h l o r i c ac id) p r o d u c e d by so lu t ion . Speak ing g e n e r a l l y , in s y s t e m s with i n t e r m e t a l l i d e s in the p h a s e d i a g r a m th i s me thod m u s t be u s e d with c a r e , s i n c e f o r m a t i o n of i n t e r m e t a t l i d e l a y e r s on the s p e c i m e n s is p o s s i b l e b e c a u s e of i n t e r a c t i o n with the m e l t .

In connec t ion wi th th i s , a s tudy was m a d e of the c o m p o s i t i o n of the t r a n s i t i o n zone f o r m e d upon i n t e r a c t i o n be tween n i cke l and I iquid t in in the t e m p e r a t u r e i n t e r v a l 300-700~ with i n t e r a c t i o n t i m e up to 4 h. At t e m p e r a t u r e s of 500, 600, 700 ~ aU t h r e e p h a s e s , Ni3Sn, Ni3Sn2, Ni3Sn4, e x i s t i n g in the e q u i l i b r i u m p h a s e d i a g r a m w e r e o b s e r v e d , whi le a t 300 and 400 ~ NiaSn 2 and Ni3Sn 4 w e r e o b s e r v e d . The p h a s e s NiaSn and Ni3Sn 2 w e r e f o r m e d by r e a c t i o n d i f fus ion be tw e e n n i cke l and tin with i s o t h e r m a l soak ing . The to ta l t h i c k n e s s of the l a y e r of t he se two p h a s e s d id not e x c e e d 5 g at 600, 700~ 3 g a t 500~ 1 g a t 300, 400~ which i n t r o d u c e d an abso lu t e e r r o r in to the c o n c e n t r a t i o n d e t e r m i n e d of 0.01, 0.006, 0.002% by weight . The Ni3Sn 4 phase was ev iden t l y f o r m e d by c r y s t a l l i z a t i o n f r o m the m e l t , a s i n d i c a t e d b y the c h a r a c t e r i s t i c j a g g e d (with p r o j e c t i o n s t o w a r d the tin) f o r m of the l a y e r . At 700~ the NiaSn 4 l a y e r had a t h i c k n e s s up to 25 g, bu t i t was e a s i l y r e m o v e d f r o m the s p e c i m e n by s c r a p i n g , and d id not a f fec t the a c c u r a c y of C d e t e r - m ina t i on .

T A B L E 1. Solut ion Ra te Cons tan t s (at w = 16 s e e - l ) , S a t u r a t i o n C o n c e n t r a t i o n s , and Nicke l Di f fus ion Coef f i c i en t s in L iqu id Tin . P a r e n t h e s e s Ind ica te Mean Square E r r o r cfK.103 c m / s e c , ~D .105 c m 2 / s e c

ToC

300 400 500 600 700

Ky I �9 103 cm/sec

4 , 3 6 ( 0 , 1 7 )

5,80(0,37) 7,73 (0,30) 9,59 (1,12)

11,08(0,97)

KNI~Sn" �9 10 3 Cffi /SeC

5,25 (0,67) 6,68 (0,44) 6,56 (0,32) 8,59 (0,19) 9,26 (0,72)

Km,Sn,: �9 103 cmlsec

5,30(0,20) 7,040(0,79) 7,70(0,68) 9,17 (0,81)

11,46 (0,93)

Cs %wt.%

0,26 0,72 1,70 3,50 6,15

D. l0 s cm2/sec

1,79 (0,14) 2, 74 (0,26) 4,12 (0,24) 5,69 (I ,00) 7,02 (0,92)

1300

L) ]

%

$ ~

A F

T~

700 600 ~00 400 500

i ,

Jo0 St/V (see/era)

o - - T- - ,

4-50

S,50

~5o t200 t ~O0 t6oo t,~Oo t/Toe tO ~

Fig. 4 Fig. 3

Fig. 3. in[Cs/(C s - C)] versus corrected solution time for nickel in liquid tin. (S/V = 0.1545-0.1518, w = 16 see -t , Re = 6170). 1) 300~ 2) 400~ 3) 500~ 4) 600~ 5) 700~

Fig. 4. Nickel and nickel stannide solution ra te constants in liquid tin versus t empera tu re (w = 16 sec- i ) .

RESULTS AND DISCUSSION

i . Solution Kinetics. The solution kinetics of nickel and its intermetallides in liquid tin were studied at temperatures of 300-700~ and a rotation rate of 146 rpm. In addition, to determine the limiting factor in the intermetallide solution process the disc rotation rate was varied over the range 146-1400 rpm at a temperature of 500~

Figure 1 shows nickel concentration in the tin melt as a function of time. It is evident that after 2 h the solution process practically attains saturation. The saturation concentrations obtained are presented in Table I. The temperature dependence of saturation concentration (in wt. %) is given by the expression (Fig. 2)

Cs= (5.344 + 0,206) exp ( 8794 RT +-- 75 ) wt.%

The heat of solution of nickel in liquid tin, calculated on the basis of these data is (8794 • 75) eel/ mole. This vaiue is lower than the heat of solution measured by the calorimetric method at 350~ [8]. Jena and Ramachendran [8] obtained a concentration dependence for the heat of solution AHNi at this tem- perature of the form

-IHN, ----- -- 11635 -{- 29400Xm-'_ 25 eel/mole,

where XNi is the nickel content as an atomic fraction. The value of AHNi calculated from this equation at XNi = 0.0035 proves to be equal to 11,530 • 25 cal/mole. The cause for this divergence between our re- sults and those of [8] remains unclear; it may possibly be due to the different methods used.

Figure 3 shows the quantity ln[Cs/(Cs - c)] as a function of corrected solution time. All points on the graph fit straight lines well, and thus the nickel solution rate constants remain the same over the entire concentration interval. After processing the results by the method of least squares, temperature depen- dences were obtained for solution rate constants of nickel and its stannides in tin:

•NI = (0.0418 _ 0.0031) exp (-- 2601 _+ 140/RT) c m / s e c KNl3S. = (0.0194 _+ 0.0033) exp (-- 1495 _ 290/RT) c m / s e c

K~,.s.o = (0.0299 _ 0.0031) exp (-- 1994 • 180/RT) c m / s e c .

The activation energies in these equations differ significantly. To ver i fy whether there is a cause for this transition to a kinetic regime, the intermetallide solution rate constant was taken as a function of angular disc rotation velocity w. It proved to be the case that this function (Fig. 5) conforms to the equation of

1301

O

% ~ zo

~0

4 5

Fig.

i 12

Y J

fo f2 $~C" i/2

700 b~,.~

ct0~

7~ ~oo 400 ~00

\

i/To/r /g:

F i g . 6

Fig. 5. Nickel stannide solution rate constant in liquid tin versus disc angular rotation velocity (T = 500~ 1) NiaSn; 2) Ni3Sn 2.

Fig. 6. Diffusion coefficient of nickel in liquid tin versus tempera- ture.

V. G. Lev i ch , Eq. (4), which is r e l i a b l e ev idence fo r the d i f fus ion c h a r a c t e r of the so lu t ion p r o c e s s [10]

K = 0.62 Dz'3 ~-l'~ ,)1/2, (4)

w h e r e D is the d i f fus ion cons t an t for a t o m s of the d i s s o l v i n g m e t a l in the m e l t and v i s the k i n e m a t i c v i s - c o s i t y of the l iqu id .

It has been e s t a b l i s h e d p r e v i o u s l y [6] tha t so lu t i on of n i cke l in t in i s a l s o l i m i t e d by d i f fus ion to w 1/2 = 10.

I t shou ld be no ted tha t a l though the d i f fus ion a c t i v a t i o n e n e r g y and v i s c o u s f low EDv of n i c k e l and the i n t e r m e t a l l i d e s d i f f e r , the so lu t ion r a t e c o n s t a n t s a t c o r r e s p o n d i n g t e m p e r a t u r e s a r e qui te c l o s e (Table 1, F ig . 4). This is a d d i t i o n a l ev idence of the d i f fus ion na tu r e of so lu t ion in a l l c a s e s .

2. Di f fus ion Coe f f i c i en t s . F r o m the da ta on n i c k e l so lu t ion r a t e c o n s t a n t s , the d i f fus ion coe f f i c i en t s D of n i cke l in l iqu id t in w e r e c a l c u l a t e d fo r t e m p e r a t u r e s of 300-700~ The equa t ion ob ta ined by K a s s n e r [9]

K = 0,554 Dm ~-,/6 r (5) /

was used.

The quantity I in Eq. (5) is an integral whose tabular values are presented as a function of the ratio D/v in [9]. The D values needed to find I were calculated with Eq. (4), which is a f irst approximation to the solution for flow on a rotating disc.

The kinematic viscosity of the melt v, used in calculating the diffusion coefficients, is the ari thme- tic mean of the viscosity of pure tin and the viscosity of the saturated tin - nickel solution at the given tem- perature. Pure tin viscosities were taken from [11], while S n - N i solution viscosities were calculated from data in [12].

The results of diffusion coefficient calculations are described by an equation (Fig. 6)

D - - (5.147-4-0.58) - 10 -4 exp (--3880.-t-210]RT).

C o m p a r i s o n with da ta p r e s e n t e d in [13] shows that the D va lues ob ta ined h e r e (Table 1) a r e l o w e r in a b s o l u t e va lue ( 2 . 7 4 . 1 0 -5 c m 2 / s e c as opposed to 6 . 8 . 1 0 -5 e m 2 / s e c at 400~ a l though the d i f fus ion a c t i v a - t ion e n e r g y of 3880 c a l / m o l e a g r e e s s a t i s f a c t o r i l y with the va lue of 4530 + 550 c a l / m o l e , p r e s e n t e d in [13].

1.

LITERATURE CITED

V. N. E r e m e n k o , Ya. V. Natanzon, R. V. Antonchenko , O. F . G a l a d z h i i , and V. R. Ryabov , in : \Ve t t ab i l i ty and Sur face P r o p e r t i e s of Mel t s and So l ids [in R u s s i a n ] , Naukova Dumka , Kiev (1972), p. 108.

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2. G.I. Barinov and P. M. Shurygin, in: Technology of Electronics Industry Materials, 2nd ed. [in Russian], Krasnoyarsk (1972), p. 71.

3. G.I. Barinov and P. M. Shurygin, New Developments in Metallurgical Process Theory and Tech- nology [in Russian], Krasnoyarsk (1973), p. 80.

4. A.V. Dean and P. I. Ennis, J. Inst. Metals, 100, Nov., 322 (1972). 5. A.I . Golyzhnikov and E. M. Smirnova, Zashehita Metallov, 1__00, No. 5, 610 (1974). 6. V.I. Itin, A.N. Tabachenko, Yu. S. Naiborodenko, and Z. G. Krutikova, in: Wettability and Sur-

face Properties of Melts and Solids [in Russian], Naukova Dumka, Kiev (1972), p. 110. 7. V.N. Eremenko and Ya. V. Natanzon, Fiz. Khim. Mekhan. Hat., 2, No. 5, 574 (1966). 8. A.K. Jena and T. F. Ramachandran, Scr. Met., 5, 639 (1971). 9. T . F . Kassner, J. Electrochem. Soc., 114, 689 (1967).

i0. V.G. Levich, Physicochemical Hydrodynamics [in Russian], Fizmatgiz (1959). 11. V.S. Chirkin, Thermophysical Properties of Nuclear Physics Materials [in Russian], Atomizdat

(1968). 12. N.M. Bokareva, T. L. Gotgil'f, K. I. Eretnov, L. A. Koledov, and A. P. Lyubimov, Izv. Vyssh.

Uchebn. Zaved., Chern. Metallurgiya, No. 9, 8 (1965). 13. C.H.Ma and R. A. Swalin, Acta Metallurgica, _8, 388 (1960).

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