X-ray study of the transformation in Ni 3 Sn phase
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9. R. L. Patterson and C. M. Wayman:Acta Met., 1966, vol. 14, pp. 347-69. 10. T. Bell and W. S. Owen: Trans TMS-AIME, 1967, vol. 239, pp. 1940-49. 11. J. S. Pascoverand S. V. Radcliffe: Trans. TMS-AIME, 1968, vol. 242, pp. 67382. 12. O. Johari and G. Thomas: Acta Met., 1965, vol. 13, pp. 1211-12.
X-Ray Study of the Transformation in Ni 3 Sn Phase J. BANDYOPADHYAY
AND
K. P. GUPTA
THROUGH the DTA measurements Heumann 1 first i n d i c a t e d a t r a n s f o r m a t i o n i n t h e NisSn p h a s e , r e p o r t e d to have MgsCd type structure, and suggested an orderdisorder type transformation. Schubert, e however, claimed a change at higher temperatures from the Mg~Cd t y p e s t r u c t u r e to FesA1 t y p e s t r u c t u r e . H a n s e n 3 on t h e o t h e r h a n d s u g g e s t e d a c p h A3 t y p e s t r u c t u r e a t the higher temperatures. In t h e p r e s e n t i n v e s t i g a t i o n a n a t t e m p t w a s m a d e to s t u d y t h e NisSn t r a n s f o r m a t i o n through X-ray diffraction work. A l l o y s of c o m p o s i t i o n NiTsSn2s a n d NiTs.sSn24.s w e r e m e l t e d f r o m 99.9 p c t N i s h o t s a n d 9 9 . 9 9 p c t p u r e Sn in an induction melting furnace under argon gas atmosphere. Since the weight losses in melting were l e s s t h a n 0.03 p e t n o c h e m i c a l a n a l y s i s w a s d o n e . T h e a l l o y s w e r e a n n e a l e d in s e a l e d a n d e v a c u a t e d q u a r t z c a p s u l e s a t 615 ~ , 700 ~, 800 ~, 805 ~, 810 ~, 960 ~, 1000 ~, a n d 1050~ t e m p e r a t u r e s c o n t r o l l e d to w i t h i n ~:I~ and subsequently water quenched. Metallographically b o t h s a m p l e s w e r e f o u n d to b e s i n g l e p h a s e . X - r a y d i f f r a c t i o n t r a c e s of t h e --325 m e s h p o w d e r a l l o y s were taken in a GE-XRD-V diffractometer using c o p p e r K a r a d i a t i o n a t 40 k v a n d 18 m a . T h e s a m e diffractometer conditions were maintained throughout to h a v e e a s i l y c o m p a r a b l e d a t a . S i n c e the a l l o y s w e r e b r i t t l e a n d t h e d i f f r a c t i o n p e a k s f o r the a l l o y s in the as-powdered and powder-annealed states were equally sharp and identical, the powders were used without annealing for taking diffraction traces. The annealing sequence, annealing time, and the relative i n t e n s i t i e s of r e f l e c t i o n s f o r e a c h a n n e a l i n g t e m p e r a t u r e a r e p r e s e n t e d i n T a b l e I. A s t h e d a t a i n d i c a t e s the diffraction patterns for all temperatures were b a s i c a l l y the s a m e a n d t h e o b s e r v e d d i f f r a c t i o n p e a k s c o u l d b e c o m p l e t e l y i n d e x e d on t h e b a s i s of a h e x a g o n a l s t r u c t u r e w i t h a0 = 5 . 2 9 ~ , Co = 4.24,~, a n d Co/ao = 0.801. The a s s i g n e d i n d i c e s m a t c h e d well w i t h t h a t r e p o r t e d f o r t h e Ni3Sn 4 a n d MnaSn s p h a s e s . H o w e v e r , the r e l a t i v e i n t e n s i t i e s of a f e w r e f l e c t i
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