Some recent results on magnetism in alloys
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Some Recent Results on Magnetism in Alloys
PAUL A. BECK
T h e e f f e c t o f l o c a l a t o m i c e n v i r o n m e n t o n t h e a t o m i c m o m e n t of F e in F e - A 1 a l l o y s a n d o f V in A u - V a l l o y s i s r e e v a l u a t e d , u s i n g i m p r o v e d m e t h o d s o f a n a l y s i s a n d n e w m a g n e t i c d a t a . M a g n e t i c c l u s t e r s w i t h g i a n t m o m e n t s o c c u r in m a n y a l l o y s in w h i c h o n e o f t h e c o m p o n e n t s h a s no m a g n e t i c m o m e n t . T h i s i s t r u e f o r FeA1 in s p i t e o f t h e p r e s e n c e of w e l l - d e v e l o p e d a t o m i c l o n g r a n g e o r d e r , a l t h o u g h t h e c o n c e n t r a t i o n of m a g n e t i c c l u s t e r s d o e s d e c r e a s e with i n c r e a s i n g long r a n g e o r d e r . The p h e n o m e n a of m i c t o m a g n e t i s m a r e r e v i e w e d . M i c t o m a g n e t i s m o c c u r s in m a n y a l l o y s h a v i n g no l o n g r a n g e a t o m i c o r d e r , a n d it i s c h a r a c t e r i z e d b y t h e f r e e z i n g of t h e s p i n o r i e n t a t i o n s a t low t e m p e r a t u r e s b u t , in c o n t r a s t to f e r r o m a g n e t i s m a n d to a n t i f e r r o m a g n e t i s m , w i t h o u t l o n g r a n g e m a g n e t i c o r d e r .
I N recent years, considerable progress has been made in the study of magnetism in alloys. In this paper three areas of experimental research with concentrated alloys of 3d metals are reviewed, in which the author has been particularly interested.
w a s f o u n d t h a t b y f a r t h e l a r g e s t p a r t of t h e s p i n m o m e n t s is c o n c e n t r a t e d at c e r t a i n a t o m i c s i t e s , Both
diffuse and low-angle magnetic neutron scattering. It
neutron diffraction and magnetization measurements indicate that the spin moments associated with the atoms of a certain 3d transition metal in its alloys may vary considerably, depending on the local atomic enviro nment. A measurable effect on the saturation magnetization of the degree of atomic order in FeNis, which can be changed by appropriate heat treatment, was noted~as early as 1939. A clear statement of the local atomic environment effect in random solid solutions was first given by Jaccarino and Walkere in connection with Nb-
Prof. PAUL A. BECK is associated with the Department of Metallurgy and Materials Research Laboratory, University of Illinois, Urbana, IlL He was born in Budapest, Hungary, and studied mechanical engineering at the Technical University in that city. He came to the United States in 1928 as a Graduate Student in Metallurgy at the Michigan Technological University. He did research work at the Kaiser-WilhelmInstitute for Metals Research in Berlin, Germany, with Prof. M. Polanyi and at the Laboratoire de Chimie Physique of the University of Paris, France. His industrial experience (a total of 8 years) was with the Central Research Laboratory of the American Smelting and Refining Co., The Beryllium Corporation, and
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