Crystallization of an Fe-Ni base amorphous alloy
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S TUDY of the nature of amorphous a l l o y s s t a r t e d in e a r n e s t in 1960 with the development of Duwez e t al ~ of a fast quenching technique f o r producing s m a l l quantities of amorphous thin foils f r o m the molten s t a t e . In the e a r l y days, the studies w e r e l i m i t e d to magnetic and e l e c t r i c a l m e a s u r e m e n t s , t h e r m a l a n a l y s i s , and s t r u c t u r a l a n a l y s i s using X - r a y and e l e c t r o n diffraction and 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 methods. Study of the m e c h a n i c a l p r o p e r t i e s did not get into full gear until r e c e n t l y when, with the advance in quenching techniques, it was p o s sible to obtain long s t r i p s or f i l a m e n t s of a l l o y s with the n o n c r y s t a l l i n e s t r u c t u r e . 2,3 The c r y s t a l l i z a t i o n behavior of the amorphous a l l o y s was a l s o one of the e a r l y topics of i n t e r e s t . Work h e r e included not only s p e c i m e n s made by fast-quenching techniques f r o m the molten state, but a l s o s p e c i m e n s made by other techniques. The e l e c t r o l e s s deposition4 and e l e c t r o deposition~ methods for producing amorphous a l l o y s were, in fact, a v a i l able even b e f o r e the quenching techniques were p e r fected. Although the number of a l l o y s that can be deposited in this way is quite limited, the advantage h e r e is that both thin foils and thick bulk a l l o y s can be made. Alloys such as N i - P , Ni-B, C o - P a r e some of the more extensively studied in this a r e a . The change of a mechanical p r o p e r t y with the p r o g r e s s of c r y s t a l l i z a t i o n f o r m e d the b a s i s for s e v e r a l p a pers.4-20 A common observation in those amorphous a l l o y s is that h a r d n e s s i n c r e a s e s with the amount of c r y s t a l l i z a t i o n . A detailed investigation of e l e c t r o l e s s l y deposited N i - P alloy by Grewal e t al 9 c l e a r l y showed that peak h a r d n e s s is a s s o c i a t e d with a fine grained Ni3P m a t r i x in the c r y s t a l l i z e d state hardened H. CHANG, R & D Scientist and S. SASTRI, Director, Chemical and MaterialsResearch Division,Boston Research and Development Laboratory',Gillette Co., Boston, Ma. 02106. Manuscript submitted October 29, 1976. METALLURGICALTRANSACTIONS A
by a fine d i s p e r s i o n of c r y s t a l l i n e Ni p r e c i p i t a t e s . A s y s t e m a t i c study of c r y s t a l l i z a t i o n behavior of fast-quenched amorphous alloys using s e v e r a l exp e r i m e n t a l techniques was f i r s t undertaken by Masumoto and Maddin 11 on P d - S i a l l o y s . They i s o t h e r mally annealed the s a m p l e below the c r y s t a l l i z a t i o n t e m p e r a t u r e and o b s e r v e d the changes in r e s i s t i v i t y , t e n s i l e strength, and m i c r o s t r u c t u r e and e s t a b l i s h e d the phases p r e s e n t . T h e i r r e s u l t s indicated that peak tensile stre
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