Embrittlement of titanium by liquid cadmium
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bottom pin s e a l e d with a soft copper plug. The c a d m i u m was i n s e r t e d into the c h a m b e r at r o o m t e m p e r a t u r e . The t e s t c h a m b e r was made of type 430 s t a i n l e s s s t e e l ; it showed no i n t e r a c t i o n with e i t h e r the t i t a n i u m s p e c i m e n s o r the liquid c a d m i u m . The s a m p l e t e m p e r a t u r e was m e a s u r e d b y P t / P t - 1 3 pct Rh t h e r m o c o u p l e s cont a i n e d in a s t a i n l e s s s t e e l tube which c a m e out through the top of the c h a m b e r through an O - r i n g s e a l . The c h a m b e r was p u r g e d with high p u r i t y a r g o n gas for 20 to 30 rain and then b r o u g h t to the d e s i r e d t e m p e r a t u r e with the e x t e r n a l f u r n a c e . As soon as the s a m p l e t e m p e r a t u r e b e c a m e s t a b i l i z e d , the s a m p l e was loaded to f a i l u r e at c o n s t a n t c r o s s h e a d speed u s i n g a table model I n s t r o n t e s t i n g m a c h i n e . The s a m p l e e l o n g a t i o n was m e a s u r e d by the d i s p l a c e m e n t of the t e s t i n g m a c h i n e crosshead. B e c a u s e the s a m p l e c h a m b e r and f u r n a c e w e r e s h o r t , the t e m p e r a t u r e at the ends of the gage length was about 25~ lower than at the c e n t e r . The s a m p l e t e m p e r a t u r e was taken to be the m a x i m u m t e m p e r a t u r e as m e a s u r e d at the t h e r m o c o u p l e at the c e n t e r of the s p e c i m e n . All s a m p l e s failed n e a r the location of this m a x i m u m t e m p e r a t u r e . At the c o n c l u s i o n of the t e s t , the s a m p l e and t e s t c h a m b e r w e r e cooled to r o o m t e m p e r a t u r e in 20 to 30 rain with the a r g o n gas flowing. The s o l i d i f i e d
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M a t e r i a l s and P r e p a r a t i o n C o m m e r c i a l l y p u r e t i t a n i u m , T i - 5 5 A , was o b t a i n e d in the f o r m of a n n e a l e d s h e e t 0.02 cm thick. The c o m p o s i t i o n of the m a t e r i a l was, in wt pct: O 0.16, H 0.006, N 0.015, Fe 0.09, C 0.05. T e n s i l e s p e c i m e n s with a t e s t s e c t i o n 0.5 c m wide by 3 c m long w e r e m a c h i n e d f r o m the s h e e t and c l e a n e d in a c e t o n e b e f o r e t e s t i n g . The a n n e a l e d s h e e t had a g r a i n s i z e of about 10 ~t, m e a s u r e d on m i c r o g r a p h s by the i n t e r c e p t method. C a d m i u m of 99.999 pct p u r i t y was obtained as -~ in. r o d s . It was used as half r o u n d s l u g s , p r e p a r e d by e i t h e r s p l i t t i n g the rods or c a s t i n g the m a t e r i a l in v a c u u m in a g r a p h i t e mold. Before use, the c a d m i u m was etched with n i t r i c acid and then washed with a c e tone.
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Test C h a m b e r and P r o c e d u r e
Thet e s t c h a m b e r is shown in Fig. 1.
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