Superplasticity in tin-zinc eutectic system
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containing Houghton type 80 heat t r e a t i n g oil was used to provide e l e v a t e d t e m p e r a t u r e s d u r i n g t e n s i l e t e s t ing. The oil contained in a dewar f o r t e m p e r a t u r e s t a b i l i z a t i o n was heated by an i m m e r s i o n h e a t e r and the t e m p e r a t u r e was c o n t r o l l e d by a t h e r m o s t a t and m o n i t o r e d by a c h r o m e l - a l u m e l t h e r m o c o u p l e . The s t a i n l e s s s t e e l t e s t module u s e d to put the s p e c i m e n in t e n s i o n below the s u r f a c e of the oil is shown in Fig. 1. A d e t a c h a b l e s t r a i g h t b a r connected to the s t a t i o n a r y load cell was coupled to the t e n s i l e s p e c i m e n so that it could be r e p l a c e d and s u b m e r g e d into the t e m p e r a t u r e bath without r e m o v i n g the oil. A hollow c y l i n d e r was attached to the t e n s i l e t e s t i n g m a c h i n e ' s c r o s s h e a d , such that it c a m e down a r o u n d the s p e c i m e n and loaded it in t e n s i o n by applying f o r c e to a stop fitted to the end of the s p e c i m e n . A f t e r the oil bath r e a c h e d a u n i f o r m s t a b l e t e m p e r a t u r e the t e n s i l e s p e c i m e n was i n s e r t e d into the oil and the c r o s s h e a d lowered u n t i l contact was made with the bottom of the t e n s i l e s p e c i m e n and the s p e c i m e n elongated. By dec r e a s i n g the c r o s s h e a d speed i n s t e p s , the e q u i l i b r i u m s t r e s s r e q u i r e d for elongation was obtained.
~AD CROSSHEAD
CELL POS/'FION
SPECIMEN LOADING POSITIO~/~
Superplasticity in Tin-Zinc Eutectic System R. J. PREMATTA, AND A. PENSE
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P. S. VENKATESAN,
This note d e s c r i b e s s u p e r p l a s t i c i t y in a e u t e c t i c t i n z i n c a l l o y m a t e r i a l c o n t a i n i n g 9.8 pct zinc and 90.2 pct tin by weight. The l i t e r a t u r e v a l u e for the t i n - z i n c eut e c t i c c o m p o s i t i o n as given by H a n s e n 1 is 9.0 pct z i n c and 91 pct tin by weight. S u p e r p l a s t i c i t y i n this m a t e r i a l was studied by m e a s u r e m e n t of total elongat i o n s and computation of s t r a i n r a t e s e n s i t i v i t y i n d i c e s a s d e s c r i b e d in a n a r t i c l e by H a r t . 2 The m o t i v a t i o n for this study was the p o s s i b l e use of complex shape p r e f o r m s for s o l d e r i n g a p p l i c a t i o n s . The m a t e r i a l was cast in the f o r m of 6.7 cm d i a m b i l l e t s u s i n g c o m m e r c i a l l y p u r e tin and zinc and then e x t r u d e d into 0.95 cm d i a m r o d s . The a v e r a g e g r a i n s i z e m e a s u r e d f r o m the m i c r o g r a p h s of the eutectic u s i n g the l i n e a r i n t e r c e p t method of H i l l i a r d 3 was found to be 1 to 2 m i c r o n s . Each rod was m a c h i n e d into s e v e r a l t e n s i l e s p e c i m e n s which were t e s t e d in an I n s t r o n T e s t i n g M a c h i n e
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