Concerning the strength of dynamic strain aging in zirconium

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u n i a x i a l t e n s i l e t e s t s , s i x a s p e c t s of d y n a m i c s t r a i n ag i n g a r e c u r r e n t l y r e c o g n i z e d . 1 T h e s e a r e 1) d i s c o n t i n u o u s p l a s t i c flow o r the P o r t e v i n - L e C h a t e l i e r e f f e c t , 2) an a b n o r m a l l y low s t r a i n r a t e s e n s i t i v i t y of the flow s t r e s s , 3) the a p p e a r a n c e of flow s t r e s s t r a n s i e n t s when the s t r a i n r a t e is a l t e r e d , 4) a b n o r m a l r a t e d e p e n d e n t w o r k h a r d e n i n g , 5) the blue b r i t t l e ef f ect, and 6) y i e l d s t r e s s p l a t e a u s on t e m p e r a t u r e v s y i e l d s t r e s s d i a g r a m s . In g e n e r a l , a ll of the ab o v e tend to o c c u r within a finite r a n g e of t e m p e r a t u r e s wh o s e l i m i t s in a given m e t a l depend on the s t r a i n r a t e and the s o l u t e c a u s i n g the s t r a i n aging. While e v i d e n c e 2-7 f o r t h e s e p h e n o m e n a e x i s t s in z i r c on i u m , a c o m p r e h e n s i v e e v a l u a t i o n of d y n a m i c s t r a i n aging in this m e t a l has not b e e n p r e v i o u s l y m a d e . This p a p e r r e p o r t s such a study in which t i t a n i u m data 8 a r e u s e d as a b a s i s f o r e s t i m a t i n g the s t r e n g t h of the d y n a m i c s t r a i n ag i n g in z i r c o n i u m . EXPERIMENTAL PROCEDURES Two g r a d e s of z i r c o n i u m , one of high p u r i t y and the o t h e r of c o m m e r c i a l p u r i t y , w e r e used. T h e s e w e r e e q u i v a l e n t in i n t e r s t i t i a l e l e m e n t c o n c e n t r a t i o n s to two c o m p o s i t i o n s of t i t a n i u m s tu d i e d e a r l i e r f l F o l l o w ing C o n r a d 9 and using z i r c o n i u m c o m p o s i t i o n v s flow s t r e s s data, I~ the o x y g e n e q u i v a l e n t s w e r e d e t e r m i n e d to be 6.0 • 10 -4 and 6.0 • 10 -s r e s p e c t i v e l y . The c o r r e s p o n d i n g oxygen e q u i v a l e n t s of the two g r a d e s of t i t a n i u m w e r e 5.0 • 10 -4 and 5.0 x 10 -3. The high p u r i t y z i r c o n i u m was obtained as c r y s t a l b a r f r o m the B e t t i s A. M. GARDE, formerly a Post Doctoral Fellow at the University of Florida, is now with the Materials Science Division, Argonne National Laboratory, Argonne, Ill. 60439. E. AIGELTINGER, formerly a Post Doctoral Fellow at the University of Florida, is now with the Department of Metallurgy, University of Melbourne, Parkville, Victoria 3052, Australia. B. N. WOODRUFF, formerly a student at the University of Florida, is now with Bechtel, Inc., San Francisco, Calif. 94119. R.E. REED-HILL, is Professor, Department of Materials Science and Engineering, University of Florida, Gainesville, Fla. 32611. Manuscript submitted February 15, 1974. METALLURGICAL TRANSACTIONS A

A t o m i c L a b o r a t o r y , W e s t i n g h o u s e C o r p o r a t i o n , and was zone m e l t e d by Dr. T. R. C a s s at the M a r t i n M a r i e t t a C o r p o r