The rate of hydrogen solution in liquid alloys
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T H E p r e s e n c e of hydrogen in m e t a l s has been of cons i d e r a b l e i n t e r e s t b e c a u s e of the wide range of effects it p r o d u c e s . The behavior of hydrogen in a m e t a l is m a r k e d by a l a r g e s o l u b i l i t y change upon s o l i d i f i c a tion. Rapid melt cooling may lead to r e t a i n e d gas which can cause d e t r i m e n t a l phenomena, i . e . , ingot p o r o s i t y and e m b r i t t l e m e n t . Careful control of gas content must t h e r e f o r e be maintained during p r o c e s s ing of the metal. Hydrogen is a useful agent in metal refining, p a r t i c u l a r l y in deoxidation. F o r h i g h - p u r i t y r e q u i r e ments, ingots a r e m e l t e d under hydrogen to m i n i m i z e the oxygen content. An example is the i n d u s t r i a l r e fining of b l i s t e r copper. C o n v e r t e r copper, containing high l e v e l s of oxygen, is t r e a t e d with hydrogen in the f o r m of h y d r o c a r b o n s . The o r i g i n a l method, known as poling, has r e c e n t l y given way to bottom-blown gas injection using a natural gas d e r i v a t i v e or ammonia. Except for studies on liquid iron, 1 few data have been obtained on hydrogen solution r a t e s in m e t a l s . Meas u r e m e n t s of this type a r e needed to support the t h e r modyrmmic data and aid in understanding the phenomena involved in c o m m e r c i a l g a s - m e t a l r e a c t i o n s . Schenck and Lange 2 studied the kinetics of hydrogen solution in solid iron, nickel, cobalt and copper. They found that a m e t a l - p h a s e diffusion model b e s t fit t h e i r data. Diffusion coefficients and activation e n e r g i e s a r e p r e s e n t e d to support t h e i r conclusions. Shirokoff, et al s studied the r a t e of reduction of liquid oxidized copper with hydrogen and carbon monoxide. The data followed a f i r s t - o r d e r c h e m i c a l r e a c t i o n model. A c o m p r e h e n s i v e t r e a t m e n t of hydrogen diffusion in liquid pure nickel, copper, s i l v e r and tin was p r e s e n t e d by S a c r i s and P a r l e e f l The r a t e of hydrogen absorption W. M. SMALL, formerly Graduate Student, The University of Michigan, is Research Engineer, Noranda Research Center, Pointe Claire, Quebec. R. D. PEHLKE is Professor and Chairman, Department of Materials and Metallurgical Engineering, The University of Michigan, Ann Arbor, Mich. 48104. This paper is based on a portion of a thesis submitted by W. M. Small in partial fulfillment of the requirements for the degree Doctor of Philosophy at The University of Michigan, 1971. Manuscript submitted May 15, 1972. METALLURGICAL TRANSACTIONS
was found to be controlled by m e t a l - p h a s e diffusion. Yamauchi and Sano 5-7 studied the deoxidation r a t e of liquid copper using hydrogen diluted with argon. In a t h r e e - p a r t study, they evaluated deoxidation kinetics under a) quiescent melt conditions, b) intensive s t i r ring and with c) holding c r u c i b l e s of v a r y i n g p o r o s i t i e s . Th
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