The portevin-le chatelier effect in carburized nickel alloys
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work by Popov and Sukhovarov I i n d i c a t e d that c a r b o n can give r i s e to the P o r t e v i n - L e C h a t e l i e r Effect in n i c k e l . R e c e n t work on h y d r o g e n a t e d n i c k e l a l l o y s 2 i l l u s t r a t e d that alloy additions of c o p p e r , cobalt, and zinc a l t e r e d the t e m p e r a t u r e range over which s e r r a t i o n s a p p e a r e d on the s t r e s s - s t r a i n c u r v e and in all c a s e s the alloy additions a t t e n u a t e d the effect. It is the purpose of this p a p e r to extend the e a r l i e r work on c a r b u r i z e d n i c k e l and c a r b u r i z e d N i - C o a l l o y s 3 by s u p e r i m p o s i n g the effects of the alloying a d d i t i o n s cobalt, copper, and zinc upon the t e m p e r a t u r e r a n g e of the P o r t e v i n - L e C h a t e l i e r Effect in c a r b u r i z e d n i c k e l . Attempts were made to r a t i o n a l i z e the r e s u l t s in t e r m s of diffusion data and the probable d i s l o c a t i o n locking m e c h a n i s m s . EXPERIMENTAL 1 m m diam w i r e s of N i - C u and Ni-Co a l l o y s were p r e p a r e d from 99.95 pct Ni shot and 99.98 pct + deoxidized Cu and 99.54 pct + Co in a m a n n e r p r e v i o u s l y d e s c r i b e d . 4 N i - Z n a l l o y s were p r e p a r e d by e q u i l i b r a t ing high purity zinc, 99.9 pct + with high p u r i t y nickel s t r i p s , 99.95 pct + (70 by 4 by 0.13 m m ) in an e v a c u ated s i l i c a capsule at 910~ for 4 weeks. T h e s e were m e l t e d in oxygen f r e e a r g o n using a high f r e q u e n c y induction f u r n a c e and a method as outlined b e f o r e , s F i n a l l y , the ingots were cold r o l l e d and given suitable i n t e r m e d i a t e a n n e a l i n g in a vacuum (10 -4 t o r r ) and then cold drawn into 1 m m diam wire. The c a r b o n l e v e l s in the nickel a l l o y s were cont r o l l e d in the r a n g e 0.020 to 0.024 wt pct by e q u i l i b r a t ing the w i r e s with an F e - C alloy c o n t a i n i n g 0.17 pct C for 8 days at 925~ u s i n g a method s i m i l a r to that p r o p o s e d by H e c k l e r and Winchellfl All s a m p l e s of 1 m m diam wire of a p p r o x i m a t e l y 0.7 g were fed into the b a s e of a l u m i n a t h e r m o c o u p l e i n s u l a t o r s . The r e s u l t a n t wire s a m p l e s were t h e r e f o r e s t r a i g h t but a f t e r the lengthy e q u i l i b r a t i o n t r e a t m e n t at the r e l a J. S. BLAKEMORE, formerly International Nickel Research Fellow, Department of Metallurgy,The University of Newcastle, New South Wales, Australia, is Research Scientist, Australian Atomic Energy Commission, Research Establishment, Lucas Heights, New South Wales. Manuscript submitted December 23, 1968. METALLURGICALTRANSACTIONS
tively high t e m p e r a t u r e were c o a r s e g r a i n e d (0.1 to 0.07 m m diam for all s a m p l e s ) . After e q u i l i b r a t i o n , s a m p l e s were a n a l y z e d for c a r b o n u s i n g the c o m b u s tion technique. The
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