Recrystallization and grain growth in titanium: I. characterization of the structure
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P R O P O S E D t h e o r e t i c a l c o n c e p t s on g r a i n b o u n d a r y m i g r a t i o n in m e t a l s a r e in r e a s o n a b l e a c c o r d with available experimental data.l'2 However, suitable data for c r i t i c a l l y e v a l u a t i n g the t h e o r i e s a r e s t i l l r a t h e r l i m i t e d . M o r e o v e r , the a v a i l a b l e d a t a a r e for the m o s t p a r t r e s t r i c t e d to fcc m e t a l s and tin. C o n s e q u e n t l y , it w a s f e l t that g r a i n growth d a t a on a hcp m e t a l such a s t i t a n i u m might p r o v i d e a d d i t i o n a l i n s i g h t into the m e c h a n i s m s o p e r a t i v e d u r i n g g r a i n growth, e s p e c i a l l y s i n c e the diffusion of the i n t e r s t i t i a l s oxygen, n i t r o g e n , and c a r b o n i s r e l a t i v e l y slow in this m e t a l 3-6 and hence t h e s e s o l u t e s m i g h t e x e r t a d r a g on a m o v i n g g r a i n boundary. It h a s b e e n r e c o g n i z e d that g r a i n growth k i n e t i c s in r e c r y s t a l l i z e d m e t a l s m a y be i n f l u e n c e d by such f a c t o r s a s s p a t i a l d i s t r i b u t i o n of g r a i n s i z e s , g r a i n s h a p e , and t e x t u r e . 7 H o w e v e r , m o s t d e t e r m i n a t i o n s of g r a i n g r o w t h do not i n c l u d e m e a s u r e m e n t s of t h e s e f a c t o r s , nor even c o n s i d e r t h e m . T h e r e f o r e , in the p r e s e n t study into the effect of i m p u r i t y content on g r a i n growth in u n a l l o y e d t i t a n i u m it w a s d e c i d e d to p e r f o r m c e r t a i n q u a n t i t a t i v e o p t i c a l m i c r o s c o p y m e a s u r e m e n t s and t e x t u r e s t u d i e s in a d d i t i o n to the u s u a l m e a s u r e m e n t s of a v e r a g e g r a i n s i z e a s a function of t i m e and t e m p e r a t u r e . Such " c h a r a c t e r i z a t i o n " of the g r a i n s t r u c t u r e i s p r e s e n t e d in t h i s p a p e r , i n c l u d i n g a l i m i t e d 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 s t u d y . The g r a i n g r o w t h k i n e t i c s a r e c o v e r e d in a s e c o n d p a p e r , P a r t II. B e s i d e s being r e l e v a n t to the g r a i n growth s t u d i e s , i n f o r m a t i o n on the g r a i n s t r u c t u r e i s i m p o r t a n t to any c o n s i d e r a t i o n
K. OKAZAKI, formerly Visiting Research Associate, Metallurgical Engineering and Materials Science Department, University of Kentucky, Lexington, Ky., is now Assistant Professor, Kyushu Institute of
Technology, Kyushu, Japan. H. CONRAD is Professor and Chairman, Metallurgical Engineering and Materials Science Department, University of Kentucky. Manuscript submitted May 7, 1971. METALLURGICAL TRANSACTIONS
of the effect of g r a i n s i z e on m e c h a n i c a l p r o p e r t i e s , which i s the s u b j e c t of a t h i r d p a p e r . E X P E R I M E N T A L PROCEDURE 1) M a t e r i a l and S p e c i m e n P r e p a r a t i o n A r a n g e
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