Crystallization of the amorphous alloys Fe 50 Ni 30 B 20 and Fe 80 oB 20
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p r e v i o u s p a p e r , the m i c r o s t r u c t u r e of the p a r t i a l l y c r y s t a l l i z e d a m o r p h o u s a l l o y Fe4oNi4oP14B6 a s e x a m i n e d 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 I was d i s c u s s e d . The (Fe, Ni)s(P, B) type b . c . t e t r a g o n a l c r y s t a l s had a c h a r a c t e r i s t i c r e c t a n g u l a r shape c a u s e d by twinning of the c r y s t a l d u r i n g growth. T h e c r y s t a l s a l s o had an i n t e r n a l s t r u c t u r e c o n s i s t i n g of p l a t e s and s p h e r o i d s and a s t i l l f i n e r s t r u c t u r e of faults o r m i c r o t w i n s . T h e s e s t r u c t u r e s w e r e p r o b a b l y the r e s u l t of s m a l l d i f f e r e n c e s in c o m p o s i t i o n g e n e r a t e d d u r i n g g r o w t h of the c r y s t a l . T h e r e was no indic a t i o n of p h a s e s e p a r a t i o n p r i o r to c r y s t a l l i z a t i o n . T h e r e w e r e , h o w e v e r , s m a l l r e g i o n s of high p h o s p h o r u s c o n c e n t r a t i o n in the a n n e a l e d alloy, 2,a and it was s u g g e s t e d that t h e s e s e g r e g a t e d r e g i o n s a c t e d a s n u c l e i for c r y s t a l l i z a t i o n . Thus, d i f f u s i o n of p h o s p h o r u s o c c u r r e d p r i o r to c r y s t a l l i z a t i o n . R e p l a c i n g p h o s p h o r u s in the Fe40Ni40P14B6 a l l o y with b o r o n in the a l l o y Fe40Ni40B2o i n c r e a s e d the s t a b i l i t y of the l a t t e r a l l o y p r e s u m a b l y b e c a u s e b o r o n d o e s not s e g r e g a t e a s r e a d i l y a s d o e s p h o s p h o r u s on h e a t i n g . 4 It might be e x p e c t e d that the a l l o y containing only b o r o n with F e and Ni or F e a l o n e would p r o d u c e c r y s t a l s of d i f f e r e n t s t r u c t u r e and, p e r h a p s , d i f f e r e n t shape when h e a t e d to 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 than t h o s e in the a l l o y with 14 p c t P and 6 pct B. To d e t e r mine the e f f e c t of m e t a l l o i d type and content on the c r y s t a l s t r u c t u r e , a l l o y s f r e e of p h o s p h o r u s w e r e p r e p a r e d in the f o r m of r i b b o n 0.0028 c m t h i c k by 0.13 c m wide by r a p i d quenct'ing f r o m the m e l t . The n o m i n a l c o m p o s i t i o n s s e l e c t e d for the study w e r e FesoNi~oBeo and FeaoB2o, in a t o m p e r c e n t . T h i s p a p e r d e s c r i b e s the r e s u l t s of a 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 e study of the e a r l y s t a g e of c r y s t a l l i z a t i o n of the two a l l o y s . EXPERIMENTAL
gen, a n n e a l e d for 2 h and s l o w l y c o o l e d . The t i m e t e m p e r a t u r e r e l a t i o n s h i p s for the i n i t i a t i o n of c r y s t a l l i z a t i o n in a 2 h a n n e a l have b e e n r e p o r t e d e l s e where.5 The 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 e s a m p l e s w e r e e l e c t r o l y t i c a
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