Solidification processing
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Solidification Processing
M. C. FLEMINGS
I n t e r a c t i o n b e t w e e n t h e o r y a n d p r a c t i c e in t h e f i e l d of s o l i d i f i c a t i o n h a s b e e n s t r o n g in r e c e n t y e a r s , t o t h e g r e a t b e n e f i t of b o t h . S o l u t i o n of i m p o r t a n t p r o b l e m s h a s r e q u i r e d c o n c e p t u a l i z i n g on g r e a t l y d i f f e r e n t s i z e s c a l e s s i m u l t a n e o u s l y , and h a s a l s o r e q u i r e d e x t e n s i v e e x p e r i m e n t a t i o n to s u g g e s t a n d j u s t i f y s u i t a b l e a p p r o x i m a t i o n s f o r t h e o r e t i c a l a n a l y s e s . S o m e a r e a s of s o l i d i f i c a t i o n w h e r e t h e o r y a n d p r a c t i c a l a p p l i c a t i o n h a v e a d v a n c e d , or are advancing nicely together are dendrite arm spacing, grain size control, columnar structures, eutectic-ltke in-situ composites, inclusion formation, macrosegregation, and non-dendritic structures.
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i s m y a i m in t h i s f i f t y - f i r s t H o w e M e m o r i a l L e c t u r e t o c o n v e y t h r e e g e n e r a l i d e a s a b o u t t h e f i e l d of s o l i d i f i c a t i o n p r o c e s s i n g . T h e f i r s t i s in t h e s p i r i t of t h e dedicated educator and researcher after whom this l e c t u r e i s n a m e d . It i s t h a t in t h i s f i e l d , a s in t h e w o r k of H e n r y M a r i o n H o w e , t h e o r y a n d p r a c t i c e h a v e e f f e c t i v e l y i n t e r a c t e d in r e c e n t y e a r s to t h e g r e a t b e n e f i t of
c o n c e p t u a l i z i n g on g r e a t l y d i f f e r e n t s i z e s c a l e s s i m u l t a n e o u s l y - - a p r o c e s s t h a t i s n o t a s e a s y a s it m i g h t f i r s ' seem. Processes at the liquid-solid interface must be v i s u a l i z e d a t t h e A n g s t r o m l e v e l ; i n c l u s i o n s a r e of m i cron scale; dendrite arm spacings are usually fractions of m i l l i m e t e r s , g r a i n s i z e s - - m i l l i m e t e r s t o c e n t i m e t e r s ; a n d c a s t i n g s o r i n g o t s a r e o n t h e s c a l e of m e t e r s .
both. Theory, backed by or emanating from experimental work, has led to new industrial processes and to solution of industrial problems. At the same time, critical industrial problems have provided stimuli for fundamental research that has changed our understanding of the f i e l d in m a j o r w a y s .
Structural features such as ingot surface finish, shrinkage, and segregation which can occur on dimensions of meters cannot be understood without at the same time understanding the processes occurring at the microscopic level.
T h e s e c o n d i d e a I w i s h t o c o n v e y i s t h a t s o l u t i o n of I m p o r t a n t p r a c t i c a l p r o b l e m s tn t h i s f i e l d h a s r e q u i r e d
The ttowe Memorial Lecture was established in 1923 by the Iron and Steel Division o f AIME. The Lecturer is selected for his outstanding contributions to the science and practice o f ir
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