Serrated yielding in nickel-1.0 wt pct titanium alloy
- PDF / 213,709 Bytes
- 2 Pages / 612 x 792 pts (letter) Page_size
- 94 Downloads / 183 Views
(I120) slip directions involved in prism slip all lie essentially in the same plane as the stress axis. Under these conditions, slip on prism planes should not cause any appreciable change in the texture of the matrix. It may be concluded therefore that M is relatively independent of strain. As the twinning shear is also constant, q~ should be nearly independent of strain. Also the increment of strain of individual twins is very small, of the order of 10-1°. Therefore t h e s u m m a t i o n ( E q . [3]) c a n be w r i t t e n a s :
i L dL Lo
rJ
Z - = dp Jfn df
[4]
or I n ( L / L o ) = dp(f - fo) and,
[5]
c o n s i d e r i n g that f o = 0 a t L - L o ,
I n ( L / L o ) = qSf = t r u e s t r a i n . Finally
[6]
note t h a t t h e s e r i e s e x p a n s i o n
l n ( 1 + Of) = ~ b f - - - + ( ~ ) 2 (Of)a3
"'"
[7]
w i l l o n l y be a p p r o x i m a t e d t o I n ( 1 + qSf) ~ qSf f o r v e r y s m a l l v a l u e s o f Of. F. J. M . B o r a t t o gratefully acknowledges t h e financ i a l s u p p o r t p r o v i d e d by t h e T e c h n o l o g i c a l C e n t e r o f M i n a s G e r a i s , C E T E C , B r a z i l . T h e c o n t r i b u t i o n of R . E , R e e d - H i l l w a s f i n a n c e d by t h e E n e r g y R e s e a r c h and Development Administration u n d e r Contract No.
AT-(40- i)- 3262. 1. R. E. Reed-Hill,J. R. Douoso, and A. M.
Garde: Met. 7~aus. , 4 , 1975, vol. 6A,
pp. 1292-94.
Serrated Yielding in Nickel-l.0 wt pct Titanium Alloy M . K. M A T T A , B. D. SHARMA, AND P . DASGUPTA S e r r a t e d yielding, frequently r e f e r r e d t o as t h e Portevin-Le Chatelier effect, has been reported in a n u m b e r o f a l l o y s y s t e m s . ~ I n t h e s e c a s e s , depending upon the s t r a i n rate and the n a t u r e of solute atoms, the load-extension c u r v e s corresponding to a t e n s i l e t e s t e x h i b i t j e r k y f l o w in a c r i t i c a l t e m p e r a ture r a n g e . A n u m b e r of explanations for s e r r a t e d M . K. MATTA is with the Metallurgy Department, Nuclear Research Centre, Inchass, Cairo, Egypt. B. D. SHARMA and P . DASGUPTA are Group Leader and Scientific Officer, respectively,Metallurgy Division, Bhabha Atomic Research Centre, Trombay, Bombay 400 0 8 5 , India, where M . K. M a t t a was formerly affiliated. B. D. Sharma is currently on temporary assignment t o KFA, 5 1 7 , Julich, West Germany. Manuscript submitted June 2 , 1976. 220-VOLUME 8A, JANUARY 1977
yielding in substitutional alloys have been suggested. These are based on dynamic strain aging involving mobile solute-mobile dislocation interaction,2'3 disl o c a t i o n - p r e c i p i t a t e i n t e r a c t i o n%S o r on f o r m a t i o n of b a n d s of localized deformation and their s u b s e q u e n t p r o p a g a t i o n o v e r t h e gage l e n g t h of t h e s p e c i m e n . 6 S e r r a t e d y i e l d i n g in n i c k e l a l l o y s h a s b e e n i n v e s t i g a t e d by P o p o v a n d S u k h o v a r o v ,~ B l a c k m o r e , 8'~ a n d S o n o n a n d S m i t h .1
Data Loading...
