Morphology of aluminum oxide particles in nickel
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o b s e r v e d in e i t h e r F e - C or F e - A 1 a l l o y s . T h i s d u c t i l i t y i n c r e a s e is p r o b a b l y due to the g e n e r a l affinity of t i t a n i u m for c a r b o n which l e a d s to the e l i m i n a t i o n of the c o a r s e c a r b i d e s contained in the l a t t e r a l l o y s . Indeed, a s i m i l a r e f f e c t has been o b s e r v e d in the p r e s e n t inv e s t i g a t i o n , F i g . 6. Although the t e m p e r a t u r e f o r 60 pct r e d u c t i o n in a r e a is not a " t r u e t r a n s i t i o n t e m p e r a t u r e " it d o e s i l l u s t r a t e the s a m e g e n e r a l b e h a v i o r p r e v i o u s l y r e p o r t e d . 1'2 It a p p e a r s that the o b s e r v e d m i n i m u m o c c u r s when the i n c r e a s e d ductility a s s o c i a t e d with the e l i m i n a t i o n of the c o a r s e c a r b i d e s and the p a r t i a l s u p p r e s s i o n of i n t e r g r a n u l a r b r i t t l e n e s s is c o u n t e r b a l a n c e d by i n c r e a s e d t i t a n i u m s o l i d - s o l u t i o n hardening. The a u t h o r w i s h e s to e x p r e s s his a p p r e c i a t i o n to P r o f e s s o r M o r r i s Cohen of the M a s s a c h u s e t t s I n s t i t u t e of T e c h n o l o g y without w h o s e continued i n t e r e s t and i n s p i r a t i o n the w o r k would not have b e e n c o m p l e t e d . He a l s o w i s h e s to e x p r e s s h i s a p p r e c i a t i o n to the V a s c o M e t a l s C o r p o r a t i o n (a T e l e d y n e Company) f o r their financial support.
p o t e n t i a l of this e l e m e n t a l addition, thus i n c r e a s i n g the a m o u n t of t i t a n i u m r e q u i r e d to c o m p l e t e l y s u p p r e s s intergranular brittleness. T i t a n i u m at l o w e r c o n c e n t r a t i o n s , while not c o m pletely suppressing intergranular brittleness, does tend to m i n i m i z e its d e l e t e r i o u s e f f e c t s . R e l l i c k and McMahon 1 have noted that c e r t a i n f u r n a c e cooled F e - T i a l l o y s exhibited far g r e a t e r ductility at -195~ than that
1. J. R. Rellickand C. J. McMahon,Jr.: Met. Trans., 1970,vol. 1, pp. 929-37. 2. P. Jolly:Met. Trans., 1971, vol. 2, pp. 241-42. 3. H. J. Rack: Sc.D.Thesis MassachusettsInstitute of Technology,Cambridge, Mass., 1968. 4. C. J. McMahon,Jr. and M. Cohen:Acta Met., 1965,vol. 13, pp. 591-604. 5. C. J. McMahon,Jr.:Acta Met., 1966,vol. 14, pp. 839-45. 6. A. Gilbert,G. J. Hahn, C. N. Reid, and B. A. Wilcox:Acta Met., 1964, vol. 12, pp. 754-55. 7. S. Floreen,H. W. Hayden,and T. M. Devine:Met. Trans., 1971,vol. 2, pp. 140306.
Morphology of Aluminum Oxide
m i n a p a r t i c l e s . T h e s u s p e n s i o n was p r o d u c e d by m e c h a n i c a l l y v i b r a t i n g a j a r containing L i n d e - A a l u m i n a p o w d e r (nominal s i z e 0.3 ~). P a r t i c l e s s m a l l e r than the n o m i n a l s i z e w e r e a d s o r b e d on the s u r f a c e of the n i c k e l f i l m . A s e c o n d l a y e r of n i c k e l w a s then
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