On the growth of the Ni-W eutectic
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Fig. 2--Indentation size and r o s e t t e a r m length a s a function of loading time on the (111) s u r f a c e of a s i l v e r s i n g l e c r y s t a l at 300°K u s i n g 0.05 g load. 1) 30 sec, 2) 10 min. location intersection s i t e s with s u r f a c e s were r e v e a l e d w i t h the m o d i f i e d L e v i n s t e i n - R o b i n s o n etchant.7 I n d e n t a t i o n c r e e p i s v e r y p r o n o u n c e d in low d i s l o c a -
On the Growth of the Ni-W Eutectic
t i o n d e n s i t y s i l v e r c r y s t a l s at s m a l l l o a d s ( 0 . 0 2 to 1.0 g ) . T h e i n d e n t a t i o n h a r d n e s s P d e c r e a s e s w i t h l o a d i n g t i m e ; as in t h e c a s e o f high t e m p e r a t u r e i n d e n t a t i o n c r e e p o f m e t a l s , 2' 3 dln_P/dlnt is c o n s t a n t m t h e time r a n g e m e a s u r e d . In addition, s t u d i e s of the s h e a r z o n e t h r o u g h d i s l o c a t i o n e t c h i n g r e v e a l e d that f o r l o a d s up t o a b o u t two g r a m s , t h e s h e a r z o n e i s c o n f i n e d e s s e n t i a l l y to t h e r o s e t t e p a t t e r n , Fig. 1. On increasing t h e indentation load, t h e s h e a r zone l o s e s the rosette configuration. Preliminary m e a s u r e m e n t s o f i n d e n t a t i o n s a t t h e l a r g e r l o a d s i n d i c a t e no t i m e dependence of h a r d n e s s . T h u s , the t i m e sensitive i n d e n t a t i o n h a r d n e s s a t l o w t e m p e r a t u r e s a p p e a r s t o be a s s o c i a t e d w i t h r o s e t t e f o r m a t i o n . T h e l e n g t h o f the r o s e t t e a r m s f o r m e d at l o w l o a d s is also t i m e depende n t , Fig, 2 . T h e a u t h o r s g r a t e f u l l y a c k n o w l e d g e t h e s u p p o r t of t h e D i v i s i o n o f R e s e a r c h , U.S. A t o m i c E n e r g y C o m m i s sion and Michigan Technological University. 1. F. Hargreaves: J. Inst. Metals, 1928, vol. 39, p . 301. 2. T. O. Mulhearn andD. Tabor: J~ Inst. Metals, 1960-61, vol. 89, p . 7. 3. A. G. Atkins, A. Silv~rio, andD. Tabor: J. Inst. Metals, 1966, vol. 94, p. 369. 4 . J. H. Westbrook andP. J. Jorgenson: Trans. TMS-AIME, 1965,vol. 233, p. 425. 5. J. W. Goffard andR. G. Wheeler: Trans. TMS-A1ME, 1959, vol. 215, p , 902 6 . W.W. Walker and L. J. Demer: Trans. TMS-AIME, 1964, vol. 230, p . 613, 7. H. J. Levinstein and W. H. Robinson: J. Appl. Phys., 1962, vol. 33, p . 3149.
c a s e , the k L - R * f u n c t i o n w o u l d be d i f f e r e n t f r o m the *R = Growth rate of the eutectic solid-liquid interface.
WILFRIED
KURZ
AND B E N N O LUX
DURING
t h e s o l i d i f i c a t i o n of a N i - W e u t e c t i c a l l o y , a c o m p o s i t e s t r u c t u r e of 6 v o l p e t W i n a N i - W
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