Diffusivity of hydrogen in liquid nickel and copper
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ficient of hydrogen in liquid nickel was determined in the range 1468~to 1550~ using a capillary/gas-reservoirtechnique. The diffusion cell was semiinfinite in length. Diffusion coefficients were calculated from measured concentration-distance measurements using the appropriate solution to Fick's Second Law. The results obtained can be represented by the following Arrhenius relationship: DNi- H = 5.00 • 10-z exp
(-9736/RT) cmZ/sec
The diffusion coefficient of hydrogen in liquid copper was m e a s u r e d at the t e m p e r a t u r e s 1101 ~ and 1201~ a l s o u s i n g a c a p i l l a r y / g a s - r e s e r v o i r t e c h n i q u e . The diffusion cell was finite in length. The v a l u e s w e r e c a l c u l a t e d f r o m a v e r a g e hydrogen c o n c e n t r a t i o n s u s i n g the a p p r o p r i a t e solution to F i c k ' s Second Law: At l l 0 1 ~
Dcu_ H = 0.99 (• 0.25) • 10 -3 cm~/sec
At 1201~
Dcu_ H = 1.26 (• 0.16) x 10 -3 cm~/sec
Diffusion data in liquid m e t a l s i s i m p o r t a n t , both f r o m p r a c t i c a l and t h e o r e t i c a l viewpoints. C o m p r e h e n s i v e r e l a t i o n s h i p s b e t w e e n r a t e s of m a s s t r a n s f e r a n d d i f f u s i v i t i e s have b e e n developed for the e x p l a n a tion of high t e m p e r a t u r e m e t a l l u r g i c a l p r o c e s s e s such a s d e g a s s i n g of liquid m e t a l s . However, the a p p l i c a tion of t h e s e r e l a t i o n s h i p s i s l i m i t e d by the v o l u m e of r e l e v a n t and r e l i a b l e data c o n c e r n i n g c h e m i c a l diffusion c o e f f i c i e n t s of s o l u t e s in liquid m e t a l s . F u r t h e r data is a l s o r e q u i r e d to d e t e r m i n e the a p p l i c a b i l i t y of p r e s e n t diffusion t h e o r i e s to p a r t i c u l a r s o l u t e s and to develop new m o d e l s . Despite both of t h e s e r e q u i r e m e n t s , l i t t l e data is a v a i l a b l e c o n c e r n i n g the diffusion of hydrogen in l i q uid m e t a l s . T h r e e i n v e s t i g a t i o n s have p r o v i d e d r e p r o ducible r e s u l t s , '-3 w h e r e two of t h e s e s t u d i e s r e f e r to the s a m e liquid m e t a l . The p r e s e n t study, t h e r e f o r e , was c a r r i e d out in an a t t e m p t to i m p r o v e this s i t u a t i o n . J. H. WRIGHT,formerly with the Nuffield Research Group in Extraction Metallurgy at Imperial College, London, England, is now with Delta Metals Research Ltd., Ipswich, England. M.G. HOCKINGis Lecturer in Metallurgy, Imperial College. This paper is based upon a thesis submitted by J. H. WRIGHTin partial fulfillment of the requirements of the degree of Doctor of Philosophy at the University of London. Manuscript submitted November 24, 1971. METALLURGICALTRANSACTIONS
LIQUID NICKEL: EXPERIMENTAL The diffusion cell design is shown in Fig. 1. T h i s is a m o d i f i c a t i o n of the cell o r i g i n a l l y d e v i s e d by Belton and Hocking, 4 and l a t e r u s e d by Schwerdtfeger, 5 and M c C a r r o n and Be
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