The Effects of Order on the Deformation of the Alloy Mg 3 Cd
- PDF / 241,088 Bytes
- 2 Pages / 613 x 788.28 pts Page_size
- 40 Downloads / 225 Views
The Effects of Order on the Deformation of the Alloy Mg3Cd J O E L P . CLARK AND MICHAEL B. B E V E R In the w o r k r e p o r t e d h e r e the d e f o r m a t i o n b e h a v i o r at r o o m t e m p e r a t u r e and 78 K of i n i t i a l l y l o n g - r a n g e o r d e r e d and s h o r t - r a n g e o r d e r e d s p e c i m e n s of the a l l o y Mg3Cd was i n v e s t i g a t e d . The d e f o r m a t i o n was c a r r i e d out in c o m p r e s s i o n , which p e r m i t t e d the s p e c i m e n s to be d e f o r m e d to l a r g e r s t r a i n s than p r e v i o u s l y r e p o r t e d in the l i t e r a t u r e for p o l y c r y s t a l l i n e s p e c i m e n s d e f o r m e d in t e n s i o n . E x p e r i m e n t a l P r o c e d u r e . W e i g h e d a m o u n t s of m a g n e s i u m and c a d m i u m (both 99.999 pct p u r e ) w e r e m e l t e d in i r o n c y l i n d e r s which had b e e n s e a l e d under v a c u u m in v y c o r c a p s u l e s . The c a p s u l e s w e r e p l a c e d in a f u r n a c e at 920 K and s h a k e n v i g o r o u s l y e v e r y 20
rain o v e r a p e r i o d of two h. T h e y w e r e then r e m o v e d f r o m the f u r n a c e and the m e l t was a l l o w e d to s o l i d i f y . The ingots w e r e hot s w a g e d at 670 K to an o u t s i d e d i a m e t e r of 0.48 cm. The i r o n s l e e v e and the s u r f a c e l a y e r of the a l l o y s w e r e m a c h i n e d off. T h e s p e c i m e n s w e r e a g a i n hot s w a g e d at 670 K to a d i a m e t e r of 0.38 c m and s p a r k m a c h i n e d into c y l i n d e r s 0.76 c m long. The a l l o y s w e r e a n n e a l e d in e v a c u a t e d p y r e x tubes in a s a l t bath at 689 K for 20 min and cooled in a i r . T h i s t r e a t m e n t p r o d u c e d an e q u i a x e d g r a i n s t r u c t u r e with an a v e r a g e g r a i n i n t e r c e p t of about 0.10 ram. L o n g - r a n g e o r d e r e d s p e c i m e n s w e r e p r e p a r e d by h e a t i n g to 430 K in an oil b a t h and cooling to r o o m t e m p e r a t u r e at a p p r o x i m a t e l y 10 K p e r h. X - r a y d i f f r a c t i o n m e a s u r e m e n t s showed that this t r e a t m e n t p r o d u c e d a high d e g r e e of o r d e r , c h a r a c t e r i z e d by a l o n g - r a n g e o r d e r p a r a m e t e r of 0.91.1 An a n t i p h a s e d o m a i n s i z e of the o r d e r of 3000A was d e t e r m i n e d from transmission electron microscopy measurements. S h o r t - r a n g e o r d e r e d s p e c i m e n s w e r e p r e p a r e d by quenching f r o m 453 K into a s o l u t i o n of i c e d b r i n e immediately before testing. A nearest-neighbor shortr a n g e o r d e r p a r a m e t e r of - 0 . 1 2 was d e t e r m i n e d by X-ray diffraction. 1 S t r e s s - s t r a i n c u r v e s w e r e obtained on an I n s t r o n t e n s i l e t e s t i n g m a c h i n e at a c r o s s h e a d s p e e d of 0.05 i n . / m i n . The s p e c i m e n s w e r e held in an i n s u l a t e d c o m p r e s s i o n c y l i n d e r , wh
Data Loading...
