The effect of solute additions on the steady-state creep behavior of dispersion-strengthened aluminum
- PDF / 888,788 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 10 Downloads / 202 Views
F . V. L E N E L , A N D G. S. A N S E L L
T h e effect of solute additions o n the steady-state c r e e p behavior of c o a r s e - g r a i n e d dispersions t r e n g t h e n e d a l u m i n u m a l l o y s was s t u d i e d . R e c r y s t a l l i z e d d i s p e r s i o n - s t r e n g t h e n e d s o l i d s o l u t i o n s were f o u n d to h a v e s t r e s s a n d t e m p e r a t u r e s e n s i t i v i t i e s q u i t e u n l i k e t h o s e o b s e r v e d in s i n g l e - p h a s e s o l i d s o l u t i o n s h a v i n g t h e s a m e c o m p o s i t i o n a n d g r a i n s i z e . T h e a d d i t i o n of m a g n e s i u m o r c o p p e r to t h e m a t r i x o f a r e c r y s t a l l i z e d dispersion-strengthened a l u m i n u m c a u s e s a d e c r e a s e in t h e s t e a d y - s t a t e c r e e p r a t e w h i c h i s m u c h s m a l l e r t h a n t h a t c a u s e d by s i m i l a r a m o u n t s of s o l u t e in s i n g l e - p h a s e s o l i d s o l u t i o n s . A l l a l l o y s e x h i b i t e d e s s e n t i a l l y a 4 . 0 p o w e r s t r e s s e x p o n e n t in a g r e e m e n t w i t h t h e m o d e l o f A n s e l l a n d W e e r t m a n . T h i s was o b s e r v e d e v e n in a l l o y s w h o s e m a t r i x s h o w s a m u c h l o w e r s t r e s s e x p o n e n t w h e n t e s t e d a s a s i n g l e - p h a s e s o l i d s o l u t i o n . T h e a c t i v a t i o n e n e r g y f o r s t e a d y - s t a t e c r e e p in d i s p e r s i o n - s t r e n g t h e n e d A 1 - M g a l l o y s , a s well as t h e s t r e s s d e p e n d e n c e , was in a g r e e m e n t w i t h t h e p h y s i c a l m o d e l o f d i s l o c a t i o n c l i m b o v e r the d i s p e r s e d p a r t i c l e s . F o r t h e d i s p e r s i o n - s t r e n g t h e n e d A 1 - C u a l l o y s , t h e a c t i v a t i o n e n e r g y f o r s t e a d y - s t a t e c r e e p s u g g e s t e d that t h e k i n e t i c s o f d i s l o c a t i o n c l i m b m a y be r e l a t e d t o t h e m o b i l i t y o f c o p p e r a t o m s i n t h e m a t r i x . E l e c t r o n m i c r o s c o p i c e x a m i n a t i o n o f the dislocation s t r u c t u r e p r e s e n t a f t e r s t e a d y - s t a t e c r e e p h a d b e e n r e a c h e d s u g g e s t e d t h a t f e w m o b i l e d i s l o c a t i o n s a r e i n v o l v e d in t h e s t e a d y - s t a t e c r e e p p r o c e s s at t h e s t r e s s l e v e l s e m p l o y e d in t h i s i n v e s t i g a t i o n .
W
H
I
L
E
t h e r e has been a g r e a t deal o f work c o n c e r n i n g t h e c r e e p b e h a v i o r o f m e t a l s a n d a l l o y s , m o s t of this effort has been d i r e c t e d t o w a r d s the s t u d y of e i t h e r p u r e m e t a l s 1'2 o r a l l o y s w h i c h r e l y o n a s i n g l e s t r e n g t h e n i n g m o d e , e . g . , e i t h e r a s o l i d s o l u t i o n type 3 o r a d i s p e r s i o n - s t r e n g t h e n e d a l l o y .4 I t w a s t h e p u r p o s e o f t h i s p r e s e n t i n v e s t i g a t i o n
Data Loading...
