Measurement of particle-matrix interface strength in TD-Nickel
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G. JUDD,
AND
G. S. ANSELL
A technique has been d e v e l o p e d for the d e t e r m i n a t i o n of the p a r t i c l e - m a t r i x i n t e r f a c e s t r e n g t h in d i s p e r s i o n - s t r e n g t h e n e d a l l o y s . The p r o c e d u r e i n v o l v e s v e r y rapid r e s i s t a n c e heating, which r e s u l t s in the n u c l e a t i o n of voids by the affect of d i f f e r e n t i a l t h e r m a l ex pansion b e t w e e n the m e t a l m a t r i x and the d i s p e r s e d phase p a r t i c l e s . The i n t e r f a c e s t r e s s e s during heating a r e a function of t e m p e r a t u r e , and thus d e t e r m i n a t i o n of m i n i m u m t e m p e r a t u r e at which d e c o h e s i o n o c c u r s p e r m i t s the e s t i m a t i o n of i n t e r f a c e s t r e n g t h . This d e t e r mination was a c c o m p l i s h e d by t e n s i l e t e s t i n g i m m e d i a t e l y a f t e r heating and the findings supported by t r a n s m i s s i o n e l e c t r o n m i c r o s c o p y of quenched s a m p l e s . The s t r e n g t h of the Ni-ThO2 i n t e r f a c e in a T D - N i c k e l a l l o y w a s found to be a p p r o x i m a t e l y 30,100 psi.
IN r e c e n t
y e a r s it has b e c o m e evident that p a r t i c l e m a t r i x d e c o h e s i o n plays an i m p o r t a n t r o l e in the m e c h a n i c a l b e h a v i o r of m a n y d i s p e r s i o n - s t r e n g t h e n e d a l l o y s . t - 4 A t ech n i q u e f o r d i r e c t m e a s u r e m e n t of the i n t e r f a c e s t r e n g t h in t h e s e t y p e s of s y s t e m s would be highly d e s i r a b l e and useful f o r the s y s t e m a t i c i n v e s tigation of individual c h a r a c t e r i s t i c s which affect int e r f a c e s t r e n g t h and hence m e c h a n i c a l p r o p e r t i e s . Hancock et al.s have recentty a t t e m p t e d such a det e r m i n a t i o n by co n t ac t angle m e a s u r e m e n t s . Voids w e r e f i r s t n u c l e a t e d around AI203 p a r t i c l e s in a m a t r i x of n i c k e l and N i - C o by c o l d - r o l l i n g o p e r a t i o n s , and then followed by a m o d e r a t e a n n e a l in g t r e a t m e n t . They a s s u m e that the voids r e l a x e d to an e q u i l i b r i u m conf i g u r a t i o n during a n n e a l i n g . T r a n s m i s s i o n e l e c t r o n m i c r o s c o p y was then used to e s t i m a t e the p a r t i c l e m a t r i x i n t e r r a c i a l e n e r g y by d e t e r m i n i n g the contact a ngle between the p a r t i c l e s u r f a c e s . T h i s a p p e a r s to be a useful technique f o r r e l a t i v e i n t e r r a c i a l e n e r g y d e t e r m i n a t i o n s , but it is difficult to q u a n t i t a t i v e l y c o r r e l a t e the work of s e p a r a t i o n of an a l r e a d y opened i n t e r f a c e with the magnitude of the i n t e r f a c e s t r e s s n e c e s s a r y f o r the n u c i e a t i o q of voids. The p r e s e n t study was u n d e r t a k e n to d e v e l o p a m e a n s of d i r e c t l y
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