Solid solutions in sputter-deposits of iron with 0 to 5 Wt Pct C
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Fig. 3--Temperature dependence of c r i t i c a l s t r a i n for d i s l o cation cell formation a n d reerystallization of tungsten.
h i g h e r r a t e a n d a m o u n t of r e c o v e r y a s t h e d e f o r m a t i o n t e m p e r a t u r e i s l o w e r e d w i t h i n the s a m e h o m o l o g o u s t e m p e r a t u r e r a n g e . It i s t o be e x p e c t e d t h a t a h i g h r e c o v e r y r a t e a s well a s t h e a b s e n c e o f d e n s e s u b g r a i n boundaries will r e d u c e t h e p r o c l i v i t y to r e c r y s t a t l i z a t i o n , u n l e s s t h e d e g r e e o f cold w o r k is i n c r e a s e d . T h i s a p p e a r s t o be s u p p o r t e d by e x p e r i m e n t a l d a t a in Fig. 3 , w h i c h s h o w t h e i n f l u e n c e o f d e f o r m a t i o n t e m p e r a t u r e b e l o w 4 0 0 ° C on t h e c r i t i c a l s t r a i n £ c r , f o r recrystallization. T h e d a t a were obtained u s i n g cylind r i c a l compression s p e c i m e n s machined from the s a m e tungsten rod. Specimens were c o m p r e s s e d v a r i o u s a m o u n t s w i t h a n a v e r a g e s t r a i n r a t e o f 0.01 p e r m i n a t 150° , 250 ° , a n d 4 0 0 ° C a n d a n n e a l e d f o r 2 h r a t 2 0 0 0 ° C . It i s s e e n that t h e c r i t i c a l s t r a i n i n c r e a s e s with d e c r e a s i n g deformation temperature. T h e temperature dependence of the c r i t i c a l s t r a i n f o r r e c r y s t a l l i z a t i o n as shown in Fig. 3 is c o n t r a r y to t h e n o r m a l e x p e r i e n c e . W o r k i n g is u s u a l l y p e r f o r m e d at h i g h e r temperatures, w h e r e t h e c r i t i c a l s t r a i n inc r e a s e s with increasing deformation temperature. T h i s is probably also true f o r t h e t u n g s t e n m a t e r i a l o f this investigation, if straining were p e r f o r m e d a b o v e 400°C. I n s u m m a r y , t h e o b s e r v e d i n f l u e n c e of d e f o r m a t i o n t e m p e r a t u r e on t h e d i s l o c a t i o n s t r u c t u r e s i n p o l y c r y s talline tungsten a f t e r deformation and recovery anneali n g a s well a s on the c r i t i c a l strain for r e c r y s t a l l i z a -
Correction
lion s u g g e s t s that for a g i v e n a m o u n t of cold work recrystallization d e p e n d s o n the distribution of d i s l o cations. If the deformation p r o d u c e s a r a t h e r homogen e o u s d i s l o c a t i o n a r r a n g e m e n t , t h e s t r u c t u r e w i l l be m o r e r e s i s t a n t to r e c r y s t a l l i z a t i o n . D e f o r m a t i o n o f t u n g s t e n a n d o t h e r bee m e t a l s in t h e d u c t i l e - b r i t t l e transition temperature r a n g e for the p u r p o s e of cont r o l l i n g r e c r y s t a l l i z a t i o n is obviously o f l i m i t e d p r a c t i c a l value. H o w e v e r , t h e r e s u l t s
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