Thermodynamic studies of liquid Zn-In-Pb Solutions. Determination of miscibility gap, isoactivity of zinc and molar ther
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the p r e v i o u s p a p e r , 1 the t h e r m o d y n a m i c p r o p e r t i e s of d i l u t e Z n - I n - P b a l l o y s within the low z i n c c o n c e n t r a tion r a n g e w e r e given. In t h e s e i n v e s t i g a t i o n s , i n t e r a c t i o n p a r a m e t e r s E In and EzPb w e r e o b t a i n e d upon e x t r a p o l a t i n g in ~Zn ~o X z n = ~. A l s o , it w a s shown t h a t g r e a t e r d e v i a t i o n s f r o m R a o u l t ' s law of liquid I n - P b s o l u t i o n s a r e p o s s i b l e than w a s d e m o n s t r a t e d in the p a p e r s of T e r p i l o w s k i and G r e g o r c z y k 2 o r W i t t i g and Scheidt. s The p o s s i b i l i t y of s i d e r e a c t i o n s o c c u r r i n g b e t w e e n the c o m p o n e n t s of e l e c t r o d e s and t h o s e of the e l e c t r o l y t e was c o n s i d e r e d , e s p e c i a l l y when the c o m p o n e n t s of the i n v e s t i g a t e d a l l o y s w e r e c l o s e to z i n c in the e l e c t r o m o t i v e s e r i e s . The e r r o r c a u s e d by s i d e r e a c t i o n s i n c r e a s e s when i n v e s t i g a t i n g m o r e dilute s o l u t i o n s and h i g h e r t e m p e r a t u r e s of m e a s u r e m e n t s . In R e f . 1, the f o r m u l a e for the a c t i v i t y c o e f f i c i e n t of z i n c w e r e o b t a i n e d f r o m d a t a on the b i n a r y s y s t e m s I n - P b , z'3 Z n - I n , 4'5 and Z n - P b . ~'~ Good a g r e e m e n t with e x p e r i m e n t a l r e s u l t s w a s o b t a i n e d when c a l c u l a t i n g
(in YZn)X7,n__ -- O" In t h e p r e s e n t e x p e r i m e n t s , the t e m p e r a t u r e r a n g e w a s i n c r e a s e d to 877 K, a s the i n v e s t i g a t i o n s w e r e c o n c e r n e d with s o l u t i o n s o v e r h i g h e r r a n g e s of component c o n c e n t r a t i o n . M e a s u r e m e n t s w e r e m a d e for 9 p s e u d o b i n a r y a l l o y s at c o n s t a n t r a t i o X p b / X i n , which r e s u l t e d in the d e t e r m i n a t i o n of the r a n g e of i m m i s c i b i l i t y in the l i q u i d s t a t e and e n a b l e d the c a l c u l a t i o n by the D a r k e n m e t h o d 8 of m o l a r t h e r m o d y n a m i c functions in the liquid Z n - I n - P b s o l u t i o n s . The v a l u e s of t h e s e functions, n a m e l y , m o l a r enthatpy and m o l a r e x c e s s f r e e e n e r g y , w e r e c o m p a r e d with the r e s u l t s c a l c u l a t e d f r o m Krupkowski's formulae. ~ Krupkowski's formulism is one of the p o s s i b l e s o l u t i o n s of the G i b b s - D u h e m e q u a tion b a s e d on the t h e r m o d y n a m i c p r o p e r t i e s of b i n a r y s o l u t i o n s (see Appendix). Z. MOSER and K. FITZNER are Vice Chairman and Research Worker, respectively, Department of Theory of Metallurgical Processes, Institute for Metal Research, Polish Academy of Sciences, Krakow, Poland. Manuscript submitted October 7, 1971. METALLURGICAL TRANSACTIONS
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