The formation of gamma phase in Vanadium Permendur
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The Formation of Gamma Phase in Vanadium Permendur H. C. F I E D L E R AND A. M. DAVIS
Fig. 3--Scanning electron m i c r o g r a p h of the fracture surface of a fully ordered FeA1 alloy deformed in compression at room temperature. T h i s t y p e of i n t e r g r a n u l a r f r a c t u r e i s e v e n m o r e d r a m a t i c a l l y i l l u s t r a t e d by the s c a n n i n g e l e c t r o n m i c r o g r a p h of F i g . 3 o b t a i n e d f r o m the f r a c t u r e s u r f a c e of a f u l l y o r d e r e d FeA1 s a m p l e w h i c h was d e f o r m e d in c o m p r e s s i o n . E v e n in t h o s e c a s e s w h e r e the g r a i n s h a v e s t i l l h e l d t o g e t h e r , the u n i o n i s r e l a t i v e l y uns t a b l e , a s c a n be s e e n by t h e n u m e r o u s d a r k a p p e a r ing c r a c k s in F i g . 3. T h e s e r e s u l t s f o r the o r d e r e d a l l o y s a r e in a g r e e m e n t with the h y p o t h e s i s put f o r w a r d e a r l i e r t h a t the g r a i n b o u n d a r i e s ~ b e i n g d i s o r d e r e d , a r e r e l a t i v e l y high e n e r g y p l a n e s with r e s p e c t to the o r d e r i n g f o r c e s c o m p a r e d to any within the g r a i n i n t e r i o r s t h e m s e l v e s and t h u s p r o v i d e the e a s i e r f r a c t u r e path. T h e p r e s e n t r e s e a r c h e f f o r t w a s s u p p o r t e d by T h e United States Atomic Energy Commission under Cont r a c t n u m b e r A T - (40-1)- 3935. T h e s c a n n i n g e l e c t r o n m i c r o s c o p e o b s e r v a t i o n s w e r e c a r r i e d out within the N o n - M e t a l l i c M a t e r i a l s D i v i s i o n of T h e U.S, N a v a l O r d n a n c e L a b o r a t o r y , W h i t e O a k , Md. F i n a l l y , the a u t h o r s w i s h to e x p r e s s t h e i r a p p r e c i a t i o n to M r . M, E. Taylor and Mr. Wen Feng Tseng for their assist a n c e d u r i n g the p r e s e n t e f f o r t . 1. w. Justusson, v. E Zackay, and E. R. Morgan: Trans. ASM, 1957, vol. 49, p. 905, 2. H. J. Leamy: Ph.D. Thesis, Iowa State University,Ames,Iowa, 1967. 3. H. J. Leamyand F. X. Kayser: Phys, Stat. Sol., 1969, vol. 34, p. 765. 4. J. H. Westbrook:Mechanical Properties of lntermetallic Compounds, J. H. Westbrook, ed., John Wiley& Sons, New York, 1960. 5. J. H. Westbrook: J. Electrochem. Soc., 1956, vol. 103, p. 54. 6. M. J. Marcinkowskiand Henry Chessin:Phil Mag., 1964, vol. 10, p. 837. 7. M. J. Marcinkowskiand D. S. Miller:Phil. Mag., 1961, vol. 6, p. 837. 8. Paul A. Flinn: Trans. TMS-AIME, 1960, vol. 218, p. 145. 9. E. C. W. Perryman:J. Inst. Metals, 1954-55, vol. 83, p. 369. 1036-VOLUME 1,APRIL 1970
V A N A D I U M P e r m e n d u r , an a l l o y of 2 pct V , 49 pct C o , 49 p c t F e , i s p r i z e d f o r i t s high s a t u r a t i o n m a g n e t i z a t i o n . A l t h o u g h the a l l o y i s e x t e n s i v e l y u s e d , s o m e of i t s m e t a l l u r g i c a l f e a t u r e s a r e not w e l l u n d e r stood. W h i l e the 50 pct C o , 50 p c t F e a l l o y i s e n t i r e l
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