Density of liquid bismuth
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SOLVUSTEMP- 59~
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QUENCHED DIRECTLy TO AGING TEMPERATURE AG#NG T~ME = 13~OMIN HYDROGEN CONC = 57 pPM
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AGING TEMPERATURE (~C)
Fig, 1--Determination of solvus temperature. E~
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c(ppm) = 8.60 • 104 ex p ( - 2 .5 2 • 103/T)
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which is v a l i d b e t w e e n 44 ~ and 300~ A so l i d line in F i g . 2 r e p r e s e n t s t h i s r e l a t i o n s h i p . Th e heat of s o l u " tion of t i t a n i u m h y d r i d e in s a t u r a t e d a - T i is 5.0 k c a l p e r m o l e f o r this r e p r e s e n t a t i o n .
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O PRESENT STUDY [ ] PATON ET A L KOSTER ET A L ~ , McQUI LLAN
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Fig. 2--Hydrogen solubility in c~-Ti. r e g i o n s w h e r e a p r e c i p i t a t e w i l l and w i l l not f o r m . The s o l v u s t e m p e r a t u r e w a s a f f e c t e d not m o r e than 1~ by aging b e t w e e n 300 and 2800 m i n . A f t e r the s o l v u s d e t e r m i n a t i o n s , the s a m p l e s w e r e sent to the L u v ac C o r p . , Newton, M a s s . f o r h y d r o g e n a n a l y s i s by v a c u u m e x t r a c t i o n . Only the r e g i o n b e t w e e n t h e p o t e n t i a l l ead s w e r e a n a l y z e d . The r e s u l t s of the s o l v u s and h y d r o g e n content d e t e r m i n a t i o n s a r e s u m m a r i z e d in F i g . 2. A l e a s t s q u a r e s fit of the p r e s e n t data to the A r r h e n i u s r e l a t i o n g i v e s the m a x i m u m s o l u b i l i t y of h y d r o g e n in a - T i in the t e m p e r a t u r e r a n g e of 60 ~ to 170~ to be c(ppm) = 4.55 • 104 exp(-2.25 • 103/T)
[1]
The heat of s o l u t i o n of t i t a n i u m h y d r i d e in h y d r o g e n s a t u r a t e d a - T i is 4.48 k c a l p e r m o l e . A n o t h e r s o l v u s t e m p e r a t u r e that d i s t i n g u i s h e s b e tween the r e g i o n s w h e r e a p r e c i p i t a t e w i l l o r w i l l not d i s s o l v e w a s a l s o d e t e r m i n e d . It w a s found that t h i s s o l v u s v a r i e s a s m u c h as 20~ depending on the h i s t o r y of h y d r i d e p r e c i p i t a t i o n . Since the s o l v u s d e t e r m i n e d by t h i s method without long t i m e aging n e a r r o o m t e m p e r a t u r e ( i . e . without the c o a r s e n i n g of p r e c i p i t a t e s ) a g r e e s within a few d e g r e e s to Eq. [1], the s o l v u s d e t e r m i n e d by the f i r s t m e t h o d can be c o n s i d e r e d a s the thermodynamic solvus t e m p e r a t u r e . METALLURGICALTRANSACT1ONS
[2]
1. R. J. Wasilewski:Trans. TMS-AIME, 1962, vol. 224, pp, 5-8. 2. E. A. Gulbransen and K. F. Andrew:Metals Trans., 1949,vol. 185, pp. 741-48. 3. N. Paton, B. S, Hickman,and D. Leslie: ScienceCenter, North AmericanRockwell Corp., Thousand Oaks, Cal., unpublished research. 4. W. KSster,
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