The interface phase in alpha-beta titanium alloys
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The Interface Phase in Alpha-Beta Titanium Alloys HAROLD MARGOLIN, ERNEST LEVINE, AND MORRIS YOUNG Recently attention has been focused o n the s t r u c t u r e o f the i n t e r f a c e r e g i o n b e t w e e n ot p a r t i c l e s a n d t h e fl m a t r i x o f or-/3 T i a l l o y s b e c a u s e o f t h e p o s s i b i l i t y t h a t t h i s a r e a , w h i c h is r e f e r r e d to as t h e i n t e r f a c e p h a s e , m a y h a v e a s i g n i f i c a n t r o l e in v a r i o u s m e c h a n i cal properties. R h o d e s and Williams 1 have reported t h a t in T i - 6 A 1 - 4 V * a s e r r a t e d n o n - B u r g e r s o r i e n t a *All compositions given in weight percent. t i o n or, d e s i g n a t e d T y p e 2or ( R e f . 2), g r o w s f r o m t h e a - / 3 i n t e r f a c e into t h e ot a n d f o r m s a t m o d e r a t e l y
HAROLD MARGOLIN is Professor, Department of Physical and Engineering Metallurgy, PolytechnicInstitute of New York, Brooklyn, NY 11201, ERNEST LEVINE is Senior Research Metallurgist, Linde Division Union Carbide, Tarrytown, NY, and MORRIS YOUNG is Metallurgist, Airco Central Research Laboratories, Murray Hill, NJ. Manuscript submitted May 2 1 , 1976. METALLURGICAL
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r a p i d c o o l i n g r a t e s ( ~ 9 0 0 ° C / h ) . T y p e lot i s t h e B u r g e r o r i e n t a t i o n ot ( R e f . 3). T h e s e a u t h o r s h a v e also r e p o r t e d t h a t a f c c p h a s e f o r m s between/3 a n d ot w h e n c o o l i n g i s s l o w e r . R h o d e s a n d W i l l i a m s 2 f o u n d t h a t T y p e 2or h a d a { I 0 i 2 } (1011) t w i n o r i e n t a t i o n w i t h r e s p e c t t o T y p e lot. T y p e 2ot t e n d e d p a r t i a l l y t o r e p l a c e T y p e lot i n a T i - l l . 6 M o a l l o y but t o r e p l a c e it c o m p l e t e l y in a T i - 1 4 M o - 6 A l a l l o y d u r i n g a g i n g at 400 t o 6 5 0 ° C . T h e a u t h o r s2 c o n s i d e r e d m e c h a n i c a l t w i n n i n g a n d n u c l e a t i o n a n d g r o w t h , but p r e f e r r e d t h e l a t t e r , a s e x p l a n a t i o n s f o r t h e f o r m a t i o n of t h e i n t e r f a c e p h a s e . R h o d e s a n d P a t o n4 h a v e c o n f i r m e d t h e findings o f R h o d e s a n d WilliamsI r e g a r d i n g both t h e s t r i a t e d a n d m o n o l i t h i c f c c l a y e r s in T i - 6 A I - 4 V . I n t h i s c o m m u n i c a t i o n we wish t o p r e s e n t s o m e of our own o b s e r v a t i o n s o n t h e i n t e r f a c e s t r u c t u r e a n d t o m a k e s o m e c o m m e n t s r e g a r d i n g t h e m e c h a n i s m of its formation and the p o s s i b l e influence of interface s t r u c t u r e o n mechanical properties. R e s u l t s o n two alloys, a b i n a r y Ti-4.3Mn and the c o m m e r c i a l Ti6AI-2Sn-4Zr-6Mo alloy are reported. T h e Ti-4.3Mn a l l o y w a s s w a g e d i n t h e or-/3 f i e l d a t 7 0 0 ° C t o p r o d u c e a n equiaxed a s t r u c t u r e a n d was subsequently a n n e a l e d f o r t i m e s up t o 200 h a t t h e s a m e t
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