Tensile deformation of amorphous nickel-palladium-phosphorous alloys
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I T has b e e n shown t h a t in a m o r p h o u s a l l o y s p l a s t i c flow o c c u r s d u r i n g d e f o r m a t i o n and f r a c t u r e t a k e s p l a c e in a r e l a t i v e l y d u c t i l e m a n n e r . ~-1~ M o r e o v e r , they d e f o r m i n h o m o g e n e o u s l y , i.e., in l o c a l i z e d r e gions due to a s t r e s s c o n c e n t r a t i o n . R e c e n t l y , m e c h a n i c a l p r o p e r t i e s and f r a c t u r e m o r p h o l o g i e s have been e x t e n s i v e l y s t u d i e d f o r v a r i o u s a m o r p h o u s a l l o y s . ~-17 H o w e v e r , the d e f o r m a t i o n m e c h a n i s m and f r a c t u r e m o d e have not a s y e t b e e n e s t a b l i s h e d . In p a r t i c u l a r , the o b s e r v a t i o n s of the i n h e r e n t l o c a l i z e d d e f o r m a t i o n bands have b e e n r e p o r t e d only in bending 2-3 and c o m p r e s s i o n tests.7-9 In this r e p o r t we p r e s e n t e x p e r i m e n t a l o b s e r v a t i o n s of the e x t e r n a l m a n i f e s t a t i o n s of the f r a c t u r e m o d e and the l o c a l i z e d d e f o r m a t i o n bands which a p pear after extension. E X P E R I M E N T A L PROCEDURE A p o w d e r m e t a l l u r g y m e t h o d was u s e d to p r e p a r e N i - P d - P t e r n a r y a l l o y s . The Ni powder was 99.999 p c t p u r e and the Pd p o w d e r was 99.99 p c t p u r e . T h e p h o s p h o r u s was r e a g e n t g r a d e r e d a m o r p h o u s m a t e r i a l . The p o w d e r w a s c o n s o l i d a t e d into a b r i q u e t in a d i e 1//4 in. in d i a m u n d e r a p r e s s u r e of 50,000 p s i . T h e s e b r i q u e t s w e r e v a c u u m e n c a p s u l a t e d in q u a r t z t u b e s a t 10 -5 T o r r and s l o w l y h e a t e d to 350~ u s i n g a h e a t i n g r a t e of 30~ and w e r e k e p t for two d a y s at t h i s t e m p e r a t u r e . T h i s p r o c e d u r e was r e p e a t e d to 550~ The s i n t e r e d s a m p l e s w e r e then m e l t e d in ~aigh p u r i t y a l u m i n a c r u c i b l e s at 1300~ with an i n d u c t i o n f u r n a c e in an a t m o s p h e r e of p u r i f i e d a r g o n . Ribbon f i l a m e n t s of t h e s e a m o r p h o u s a l l o y s w e r e o b t a i n e d by a m o d i f i e d P o n d m e t h o d . ~8 The r e s u l t i n g f i l a m e n t s w e r e 15 to 50 /~ t h i c k and 0.05 to 0.5 m m wide depending upon the c o m p r e s s e d a i r p r e s s u r e , the d r u m s p e e d and the e j e c t o r t i p d i a m e t e r . T h e quenched f i l a m e n t s w e r e c a r e f u l l y e x a m i n e d by X - r a y and e l e c t r o n d i f f r a c t i o n t e c h n i q u e s to d e t e r m i n e the n a t u r e of the a m o r p h o u s s t r u c t u r e . To study the p r o p e r t i e s of the a m o r p h o u s N i - P d - P s y s t e m , m a t e r i a l s w i t h the following s y s t e m c o m p o s i t i o n s w e r e p r e p a r e d : NissPd35P~o and Ni63Pd~vP2o. F o r e a s e of o b s e r v a t i o n both the n a r r o w an
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