Magnetic Susceptibility of Iron-Nickel Alloys in Liquid and Solid States

Abstract

The magnetic susceptibilities of various Fe-Ni alloys have been measured through their melting points up to 1600°C. The susceptibilities of the alloys with less than 60 % Ni increase discontinuously on melting, while those of the alloys with more than 60 % Ni decrease. The temperature variation of the susceptibilities is approximately expressed by the Curie-Weiss law in the liquid state as well as in the solid state, but the Curie constants and the paramagnetic Curie temperatures of liquids are in general different from those of solids. These results can be explained by assuming that the atomic magnetic moments remain unaltered and that the magnetic interaction varies with the interatomic distance as indicated by the Bethe-Slater curve. The change of susceptibility at the melting point is solely due to the difference in interatomic distance between the liquid and the solid. It is expected, in some cases, that the especially strong dependence of the magnetic interaction on the interatomic distance results ...