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Submitted on 1 Jan 1982
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STRESS-INDUCED MARTENSITIC
TRANSFORMATION AND A NEW 7-LAYER MARTENSITE PHASE IN THE 63.1Ni-Al ALLOY
V. Martynov, K. Enami, L. Khandros, A. Tkachenko, S. Nenno
To cite this version:
V. Martynov, K. Enami, L. Khandros, A. Tkachenko, S. Nenno. STRESS-INDUCED MARTENSITIC TRANSFORMATION AND A NEW 7-LAYER MARTENSITE PHASE IN THE 63.1Ni-Al ALLOY.
Journal de Physique Colloques, 1982, 43 (C4), pp.C4-659-C4-660. �10.1051/jphyscol:19824106�. �jpa-
00221961�
JOURNAL DE PHYSIQUE
ColZoque C4, suppZ6ment au n o 12, Tome 4 3 , de'cembre 1 9 8 2 page C4-659
STRESS-INDUCED MARTENSITIC TRANSFORMATION AND A NEW 7-LAYER MARTENSITE PHASE IN THE
63.1Ni-A1ALLOY
V . V. ~ a r t ~ n o v * , K. ~ n a m i ~ , L . G. ~ h a n d r o s *
,
A.V. ~ k a c h e n k o * and S. Nenno** I n s t i t u t e of Metal Physics, Academy of Sciences Ukr.SSR, Kiev, USSR
**Department o f Materials Science and Engineering, Osaka University, Suita, Japan
(Accepted 27 September 1982)
I t i s w e l l known t h a t t h e n i c k e l - r i c h Ni-A1 6 p h a s e a l l o y e x h i b i t s t h e marten- s i t i c t r a n s f o r m a t i o n and t h e c r y s t a l s t r u c t u r e s o f t h e as-quenched m a r t e n s i t e s a r e
~ l o ( a $ ) and 2H, ( 1 , 2 ) . However, t h e r e i s no s y s t e m a t i c i n v e s t i g a t i o n on t h e deforma- t i o n b e h a v i o u r and s t r e s s - i n d u c e d m a r t e n s i t i c t r a n s f o r m a t i o n i n t h i s a l l o y s y s t e m , o t h e r t h a n t h e d e f o r m a t i o n b e h a v i o u r o f t h e a; m a r t e n s i t e ( 3 ) . R e c e n t l y we i n v e s t i - g a t e d t h e d e f o r m a t i o n b e h a v i o u r and t h e s t r e s s - i n d u c e d m a r t e n s i t i c t r a n s f o r m a t i o n of t h e s i n g l e c r y s t a l s o f t h e 6 3 . l a t . % N i - A 1 a l l o y and found a new m a r t e n s i t e p h a s e h a v i n g a m o n o c l i n i c 7 - l a y e r s t r u c t u r e , by means o f t e n s i l e t e s t i n g , i n s i t u X-ray d i f f r a c t i o n and o p t i c a l microscopy. The d e t a i l e d p r o c e d u r e s o f t h e p r e p a r a t i o n o f t h e a l l o y a r e t h e same a s d e s c r i b e d i n ( 3 ) . The Ms t e m p e r a t u r e o f t h e p r e s e n t a l l o y was found t o b e about 253K. A l l e x p e r i m e n t s were done a t r . t . , i . e . above Ms.
I t was o b s e r v e d t h a t i n t h e specimen whose t e n s i l e a x i s was o r i e n t e d a l o n g [001]82 d i r e c t i o n , s t r e s s - i n d u c e d t r a n s f o r m a t i o n t a k e s p l a c e d u r i n g e l o n g a t i o n by f o r m a t i o n and moving of "X-shaped" zone which s e p a r a t e s t r a n s f o r m e d and u n t r a n s f o r m e d r e g i o n s , F i g . 1 . The f u l l y t r a n s f o r m e d r e g i o n c o n s i s t s o f t h e s i n g l e c r y s t a l o f t h e u i ( L l o ) m a r t e n s i t e w i t h i t s ' c l a x i s a l o n g t h e t e n s i l e a x i s d i r e c t i o n . I n t h e i n t e r - m e d i a t e "X-shaped" zone, it was found by t h e y X - r a y o s c i l l a t i n g c r y s t a l method t h a t a new 7 - l a y e r p h a s e i s p r e s e n t a l o n g w i t h t h e a2 m a r t e n s i t e , F i g . 2 . I n t h i s c a s e t h e t o t a l e l o n g a t i o n a f t e r t h e specimen was f u l l y t r a n s f o r m e d was a b o u t 12% and i s i n good agreement w i t h B2 t o L l o l a t t i c e t r a n s f o r m a t i o n . When t h e t e n s i l e a x i s i s
[Oll]B2 d i r e c t i o n , t h e maximum e l o n g a t i o n does n o t exceed 5 % , and t h e s t r e s s - i n d u c e d m a r t e n s i t e i s t h e 7 - l a y e r m o n o c l i n i c p h a s e . I t was shown t h a t t h e c r y s t a l s t r u c t u r e o f t h e 7 - l a y e r p h a s e h a s t h e 52 s t a c k i n g o r d e r which can be r e g a r d e d a s t h e Llo
l a t t i c e h a v i n g r e g u l a r s t a c k i n g f a u l t s ( 2 p e r e a c h 7 l a y e r s ) i n one of f o u r p o s s i b l e . ( 1 1 1 ) ~ l o p l a n e s , and h a s a m o n o c l i n i c symmetry. L a t t i c e p a r a m e t e r s a r e found t o be;.
a = 0 . 4 1 8 , b=0.271, c=1.448 nm, and @ = 9 4 . 3 " . I t was a l s o found t h a t t h i s 7 - l a y e r ( 5 2 ) phase formed i n some c a s e s w i t h o u t a p p l y i n g s t r e s s . I t i s r e a s o n a b l e t o c o n s i d e r t h a t t h e 7 - l a y e r p h a s e f s t h e " i n t e r m e d i a t e " m a r t e n s i t e p h a s e which forms p r i o r t o t h e f o r m a t i o n o f t h e a 2 m a r t e n s i t e , b e c a u s e t h e t e m p e r a t u r e r a n g e i n which t h e 7 - l a y e r p h a s e e x i s t s i s v e r y narrow and i t c o u l d n o t b e found when t h e a l l o y was c o o l e d below Mf.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19824106
(24-660 JOURNAL DE PHYSIQUE
Tensllc n x i b [ O i l 1 1 8
2
- Fig.2 X-ray oscillation photograph Fig.1 Optical micrograph of the X-shaped taken from the X-shaped zone, showing
diffraction spots of 7-layer (52) phase zone appeared during elongation. Tensile
axis //[001]B2. besides those of Llo martensite.
Oscillation axis // [001]Llo, Cu Ka.
1. K.Enami S.Nenno and K.Shimizu: Trans .JIM., E(1973), 161.
2. M.Chandrasekaran and K.Mukherjee: Mat.Sci. and Engineering, s(1974), 197.
3. K.Enami,V.V.Martynov,T.Tomie, L.G.Khandros a n d S . N e n n o : T r a n s . J I M . , z ( 1 9 8 1 ) , 357.
