Heat capacity of liquid bismuth
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Heat Capacity of Liquid Bismuth HOWARD
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(b) Fig. 3--Effect of r e p l i c a tilt a n g l e on fractographic a p p e a r ance. (a) Zero d e g t i l t ; (b) 30 d e g tilt. Magnification ~5700 times. a r e k n o w n t o b e q u i t e s e n s i t i v e to t h e e f f e c t o f a t m o s p h e r i c m o i s t u r e , a n o r d e r o f magnitude r e d u c t i o n in c r a c k g r o w t h r a t e a s s o c i a t e d w i t h a c h a n g e in t e s t e n v i r o n m e n t , f r o m a i r t o v a c u u m , i s p o s s i b l e .4-7 T h e striations, if p r e s e n t at t h e r e d u c e d r a t e o f growth, m a y not h a v e b e e n r e s o l v a b l e . T h e s e r e s u l t s , a l o n g w i t h a d d i t i o n a l f r a c t o g r a p h i c r e s u l t s in o t h e r e n v i r o n m e n t s , s u g g e s t that the mechanism for fatigue-crack g r o w t h in t h e T i - 6 A 1 - 4 V a l l o y i s b a s i c a l l y s i m i l a r ( s t r i a t i o n s a r e o b s e r v e d ) f o r a wide r a n g e of e n v i r o n m e n t s . I n a d d i t i o n to " v a c u u m " , t h e s e e n v i r o n m e n t s include distilled w a t e r , " d r y " a n d " w e t " air, " d r y " hydrogen, " d r y " oxygen, and " d r y " and " w e t " a r g o n . T h e a u t h o r s wish t o e x p r e s s t h e i r a p p r e c i a t i o n t o Mr. C. M . H u d s o n for c a r r y i n g out t h e experiments in v a c u u m at NASA L a n g l e y R e s e a r c h C e n t e r , a n d to Mr. R. Korastinsky for electron-microfractography. S u p p o r t f o r t h i s w o r k by the N a t i o n a l A e r o n a u t i c s a n d S p a c e A d m i n i s t r a t i o n u n d e r G r a n t N G L 3 9 - 0 0 7 - 0 4 0 is gratefully acknowledged. 1. R. M. N. Pelloux: J. Eng. Frac. Mech., 1970, vol. 1, no. 4 , pp. 697-704. 2 . D. Meyn: Trans. ASM, 1968, vol. 61, no. 1, pp. 52.61. 3 . D. Brock: J. Eng. Frac. Mech., 1970, vol. 1, no. 4 , pp. 691-96. 3230-VOLUME 2 , NOVEMBER 1971
BELL AND R A L P H HULTGREN
K N O W L E D G E of the heat capacity, Cp, of l i q u i d b i s m u t h is n e e d e d f o r i t s p o s s i b l e u s e a s a r e a c t o r c o o l a n t e i t h e r in e l e m e n t a l f o r m o r in a e u t e c t i c w i t h l e a d ;1 o r a s a n alloy with u r a n i u m a s a l i q u i d m e t a l f u e l .2 S c i e n t i f i c a l l y , t h e C p o f b i s m u t h i s o f i n t e r e s t b e c a u s e o f i t s non c l o s e - p a c k e d s t r u c t u r e i n t h e s o l i d s t a t e and its d e c r e a s e of v o l u m e on melting. P r e v i o u s m e a s u r e m e n t s o f t h e h e a t c a p a c i t y of l i q u i d b i s m u t h d i f f e r considerably, see Fig. 1. Carp e n t e r a n d H a r l e3 (1932) f o u n d t h e C~ d e c r e a s e d -4 s t e a d i l y t o 6 4 4 ° K ; F o r s t e r a n d T s c h e n t k e (1940) o b t a i n e d r e s u l t s a b o u t 8 pct h i g h e r w i t h C p d e c r e a s i n g to 6 9 0 ° K , t h e n i n c r e a s i n g a b o v e t h a t t e m p e r a t u r e . P e r s o ns (1848) v e r y e a r l y f o u n d a n i n t e r m
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