Diffusion of managenese and silicon in liquid iron over the whole range of composition
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-13,000/RT)
cm2/sec
T h e c o n c e n t r a t i o n d e p e n d e n c e of m a n g a n e s e d i f f u s i v i t y f o r t h e s a m e s y s t e m a t 1600°C m a y be expressed as D F e _ M n = { 5 . 4 8 -- 0 . 0 1 3 7 (% M n ) + 0 . 0 0 0 2 7 6 (% Mn) 2} × 10 - s c m 2 / s e c T h e t e m p e r a t u r e d e p e n d e n c e o f s i l i c o n d i f f u s i v i t y f o r the F e - S i b i n a r y s y s t e m i n the t e m p e r a t u r e r a n g e 1550° t o 1 7 2 5 ° C a t v a r i o u s c o n c e n t r a t i o n s i s a s f o l l o w s : DFe_Si
= 2.8 × 10-3 e x p
DFe__Si = 2.1 × 10-3 e x p DFe_St
= 5.1 × 10-4 e x p
(-ll,900/RT) c m 2 / s e c a t 20 p c t Si (-13,200/RT) c m Z / s e c a t 12.5 p c t Si (-9,150/RT) c m 2 / s e c a t 2 . 2 p c t Si
S E V E R A L s i g n i f i c a n t a t t e m p t s h a v e b e e n made to m e a s u r e the d i f f u s i v i t i e s o f m a n g a n e s e a n d s i l i c o n i n m o l t e n i r o n . T h e r e s u l t s s h o w that t h e d i f f u s i v i t i e s a r e of t h e o r d e r o f m a g n i t u d e e x p e c t e d f o r s i m p l e l i q u i d s , that i s , 10 -5 sq c m p e r s e c , but t h e n u m e r i c a l v a l u e s vary considerably. T h e reported m e a s u r e m e n t s i n c l u d i n g t h e c o r r e s p o n d i n g i n v e s t i g a t o r s a r e shown in T a b l e s I a n d II. A t this writing, t h e r e are only two m e a s u r e m e n t s r e p o r t e d f o r m a n g a n e s e in t h e F e - M n b i n a r y s y s t e m i n t h e c o m p o s i t i o n r a n g e 0 t o 4 wt p c t M n , 1'2 a n d no e n e r g y of a c t i v a t i o n f o r d i f f u s i o n h a s been reported. T h e r e s u l t s , however, differ c o n s i d e r a b l y . O n e i s i n o r d i n a t e l y h i g h a n d the o t h e r i s u n r e a s onably low. T h e r e h a s b e e n o n l y o n e t h e r m o d y n a m i c s t u d y m a d e 3 o v e r the w h o l e r a n g e of c o m p o s i t i o n f o r the F e - M n b i n a r y s y s t e m and on the basis of regular s o l u t i o n the r e s u l t s w e r e a v e r a g e d4 g i v i n g a s l i g h t p o s i t i v e d e v i a t i o n f r o m R a o u l t ' s l i n e . A l t h o u g h the d e v i a t i o n c a n be p r e d i c t e d by e l e c t r o n i c c o n s i d e r a t i o n , no o t h e r d a t a h a v e b e e n r e p o r t e d t o t h i s e f f e c t . M e a s u r e m e n t of t h e d i f f u s i v i t y o v e r t h e w h o l e o f c o m p o s i t i o n , however, c o u l d indirectly demonstrate t h e b e h a vior of the s y s t e m . FELIPE P . CALDERON, formerly Graduate Student, University of T o k y o , T o k y o , Japan, is now Assistant Professor of Metallurgical Engineering, University of the Philippines. NOBUO SANO and YUKIO MATSUSHITA are Associate Professor and Professor, respectively,Department of Metallurgy and Materials Science, University of T o k y o . This paper is based on a portion of a thesis submitted by FELIPE P . CALDERON in partial fulfillment of the requirements for the degree of Doctor of Engineering a
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