The effects of annealing on cold-worked Zr 3 Al
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b a r z i r c o n i u m and a l u m i n u m of 99.999 pct p u r i t y by n o n c o n s u m a b l e a r c melting; t h e i r m a i n i m p u r i t i e s (in ppm) w e r e oxygen (-200), i r o n (~100), hafnium (-~45), c a r b o n (-~50), copper (-~20) and c h r o m i u m (---15). Slabs of the ingot, 12 m m i n t h i c k n e s s , were r o l l e d in a i r at 1423 K to 4 m m s t r i p , a b r a d e d to r e m o v e oxide, and t h e n t r a n s f o r m e d to Zr3A15 by a n n e a l i n g at 1160 K for 24 h at 2.6 • 10 -4 Pa. Subsequently, the t r a n s f o r m e d m a t e r i a l was abraded, e l e c t r o c h e m i c a l l y polished 14 and then c o l d - r o l l e d (at ---2 pct r e d u c t i o n in a r e a p e r p a s s ) to t r u e s t r a i n s * of 0.05, 0.12, 0.29 *Truestrain9 is definedas ln(Ao/Af)whereA o andAfare the initialand finalcross-sectionalareas,respectively. and 0.48. Edge c r a c k i n g p r e c l u d e d h i g h e r s t r a i n s . The h i g h - p u r i t y buttons were v a c u u m a n n e a l e d at 1160 K for 24 h a f t e r which 2 m m s l i c e s were r e moved, e l e c t r o c h e m i c a l l y polished and then coldr o l l e d to a t r u e s t r a i n of 0.29. The c o l d - r o l l e d a l loys were e n c a p s u l a t e d in VYCOR and i s o t h e r m a l l y a n n e a l e d at 2.6 • 10-4 P a at t e m p e r a t u r e s f r o m 573 to 1160 K. A p a r t i c u l a r l y i m p o r t a n t point of p r o c e d u r e i s the e l e c t r o c h e m i c a l r e m o v a l of d e f o r m e d s u r f a c e l a y e r s p r i o r to r o l l i n g . If not followed, s t r a i n s above ~-0.05 to 0.10 cannot be achieved b e c a u s e of c r a c k i n g . Vickers diamond hardness measurements were made at r o o m t e m p e r a t u r e u s i n g a 30 kg load on s p e c i m e n s m o u n t e d in b a k e l i t e and on s e c t i o n s which had b e e n p o l i s h e d to the level of 600 g r a d e SiC p a p e r and o r i e n t e d t r a n s v e r s e to the r o l l i n g d i r e c t i o n . Eight m e a s u r e m e n t s were made p e r s p e c i m e n , c a r e b e i n g t a k e n to avoid overlap. U n l e s s o t h e r w i s e noted, s e p a r a t e s a m p l e s w e r e used for each d i f f e r e n t a n n e a l . T e n s i l e t e s t s on flat s p e c i m e n s (1.7 • 1.7 • 10 m m gage d i m e n s i o n s ) having grooved ends 15 w e r e p e r f o r m e d at r o o m t e m p e r a t u r e u s i n g a floor model I n s t r o n m a c h i n e . P r i o r to t e s t i n g , the s p e c i m e n s w e r e e l e c t r o c h e m i c a l l y polished for r e a s o n s des c r i b e d e l s e w h e r e 11 and then m e a s u r e d for h a r d n e s s . M i c r o s t r u c t u r e s w e r e 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 u s i n g a Hitachi HU-11A m i c r o scope at 100 kV. T h i n foils w e r e p r e p a r e d as des c r i b e d e l s e w h e r e o6 To obtain a value for the a v e r a g e v o l u m e f r a c t i o n r e c r y s t a l l i z e d for a given a n n e a l , the
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