Internal friction and strain aging of ferrous austenite
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j e r k y flow is o b s e r v e d in m e c h a n i c a l t e s t i n g (as do c o l d - w o r k p e a k s in bcc m a t e r i a l s ) . A f t e r W e f t , 3 we w i l l hereafter designate these peaks as "bound-pair" peaks and u s e the a b b r e v i a t i o n bpp in f u r t h e r d i s c u s s i o n s . The above r e v i e w s u g g e s t s the need f o r s y s t e m a t i c i n v e s t i g a t i o n of i n t e r n a l f r i c t i o n and s t r a i n aging of i n t e r s t i t i a l s o l u t i o n s of fcc m a t e r i a l s . In the p r e s e n t s t u d y , we have p r o v i d e d s o m e of this i n f o r m a t i o n for a p a r t i c u l a r c l a s s of fcc m a t e r i a l s . We have e x a m i n e d the influence of quenching, cold w o r k , and e l e c t r o n i r r a d i a t i o n on b p p ' s in F e - N i - C and F e - N i - C r - C a l l o y s and have c o r r e l a t e d t h i s w o r k with e x i s t i n g s t u d i e s on d y n a m i c s t r a i n aging and s e l f diffusion in s i m i l a r m a t e r i a l s . Two n a t u r a l c o r o l l a r i e s of t h i s i n v e s t i g a t i o n w e r e 1) to obtain new i n f o r m a t i o n p e r t i n e n t to u n d e r s t a n d i n g the m e c h a n i s m of b p p ' s and 2) to d e t e r m i n e if c o l d - w o r k p e a k s e x i s t in the i n t e r n a l f r i c t i o n s p e c t r u m of the a u s t e n i t i e s . In the f i r s t i n s t a n c e , t h e r e h a s been s o m e c o n t r o v e r s y a s to w h e t h e r o r not c a r b o n - v a c a n c y c o m p l e x e s a r e involved in the m e c h a n i s m of b p p ' s in a u s t e n i t e s . 8-~~ In the l a t t e r i n s t a n c e , c o n s i d e r a t i o n of S c h o e c k ' s a t m o s p h e r e d r a g g i n g m o d e l , 1. which i s g e n e r a l l y a c c e p t e d a s the m e c h a n i s m of c o l d - w o r k p e a k s in bcc m a t e r i a l s , s u g g e s t s such a p e a k should o c c u r g e n e r a l l y in o t h e r s o l i d s o l u t i o n a l l o y s . EXPERIMENTAL I n t e r n a l f r i c t i o n m e a s u r e m e n t s w e r e m a d e in f r e e d e c a y in a v a c u u m K 6 - t y p e t o r s i o n p e n d u l u m o v e r the t e m p e r a t u r e r a n g e of 25~ to 500~ a t a f r e q u e n c y of ~1 Hz. The m e a s u r e m e n t s w e r e m a d e on heating at an a v e r a g e r a t e of ~ 6 0 ~ with a m a x i m u m t e m p e r a t u r e g r a d i e n t along a s i x inch s p e c i m e n of 2~ A d e t a i l e d d e s c r i p t i o n of the p e n d u l u m is given e l s e w h e r e . 12 The b a s e m a t e r i a l s e x a m i n e d included F e - 3 0 and 36 p c t Ni a l l o y s , c o m m e r c i a l I n v a r , and a 310 a u s t e n i t i c s t a i n l e s s s t e e l . T h e c o m p o s i t i o n s of t h e s e m a t e r i a l s a r e given in T a b l e I. W i r e s p e c i m e n s of 0.040 in. d i a m 1 1 e t e r w e r e p r e p a r e d f r o m -8- to ~ in. d i a m r o d s of t h e s e m a t e r i a l s by s w a g i n g with i n t e r m e d i a t e a n n e a l i n g a s
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