Effects of electron irradiation on precipitation in Ni-Al alloys
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d a t a will be d i s c u s s e d in t e r m s of the b a s i c p r o c e s s e s which can o c c u r d u r i n g i r r a d i a t i o n and t h e i r t h e o r e t i cal predictions. 2. E X P E R I M E N T A L DETAILS The b i n a r y Ni-A1 a l l o y s u s e d in this study contained 8 wt pct A1 (16 a t . pct) and 6.35 wt pct A1 (13 a t . pct A1) and a r e d e s c r i b e d e l s e w h e r e , l ~ Sheets cut f r o m the r o d w e r e s a n d e d to a f i n a l t h i c k n e s s of 500 /zm. Sheet s p e c i m e n s w e r e e i t h e r s p a r k cut in the f o r m of d i s c s , 3 m m in d i a m , o r punched f r o m thin s h e e t s t o c k . S p e c i m e n s w e r e given a s o l u t i o n t r e a t m e n t at 1200~ f o r one half hour in v a c u o and w a t e r quenched. R a p i d quenching, a c c o m p l i s h e d by b r e a k ing q u a r t z c a p s u l e s in w a t e r , s u p p r e s s e d ~' f o r m a tion in the 6.35 wt pct a l l o y . H o w e v e r , the o b s e r v a tion of diffuse s u p e r l a t t i c e s p o t s in e l e c t r o n d i f f r a c tion p a t t e r n s of the 8 wt pct a l l o y showed they s t i l l contained s m a l l p a r t i c l e s of ~,'. F o l l o w i n g the heat t r e a t m e n t , s p e c i m e n s w e r e p r e p a r e d by the twin j e t technique for 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 . E l e c t r o p o l i s h i n g was c a r r i e d out at 55 V in 250 m l m e t h y l alcohol, 150 m l butyl alcohol, and 10 m l p e r c h l o r i c acid, m a i n t a i n e d at low t e m p e r a t u r e (- 50~ in o r d e r to p r e v e n t the i n t r o d u c t i o n of h y d r o g e n . I r r a d i a t i o n 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 w e r e p e r f o r m e d in a H i t a c h i HU-650B high v o l t a g e e l e c t r o n m i c r o s c o p e o p e r a t i n g at 650 kV. T h i s m i c r o s c o p e was equipped with a h e a t i n g s t a g e so that it was p o s s i b l e to c a r r y out s i m u l t a n e o u s e l e c t r o n b o m b a r d m e n t and e x a m i n a t i o n of the s p e c i m e n i n s i t u at n o r m a l aging t e m p e r a t u r e s f r o m r o o m t e m p e r a t u r e to about 800~ E a c h s p e c i m e n was e x a m i n e d in two a r e a s d u r i n g i r r a d i a t i o n : the i r r a d i a t e d a r e a and a n o t h e r a r e a at l e a s t 20 ~ m away f r o m the f o r m e r f o r c o n t r o l p u r p o s e s . I r r a d i a t e d a r e a s w e r e 3 to 4000A in t h i c k n e s s as m e a s u r e d by s t e r e o m i c r o s copy, thick enough to avoid s e r i o u s s u r f a c e d e n u d ing e f f e c t s and thin enough to avoid o v e r l a p p i n g of precipitate images.
ISSN 0360-2133/78I1211-1749500.75/0 9 1978 AMERICAN SOCIETY FOR METALS AND THE METALLURGICALSOCIETY OF AIME
VOLUME 9A, DECEMBER 1978-1749
Fig. 1--Effects of high flux irradiation at 500~ on a solution-treated and waterquenched specimen of Ni6.35 wt pct A1 to a dose of 1.1 dpa. Bright field electron micrograph, foil normal [001],
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