永久磁石Vicalloyの磁気異方性と保磁力について

Abstract

Cr-Vicalloy specimens composed of 12%(Cr+V), 52%Co, balance Fe were air-cooled from 1100°C, reduced to 90% by cold rolling and then subjected to tempering at temperatures between 100° and 800°C.The changes in the saturation induction, residual induction, coercive force and torque curves have been measured by many workers. The coercive force reaches a maximum (about 300 Oe) by tempering at 500°∼600°C.The direction of easy magnetization in the rolled state is perpendicular to the rolling surface, and becomes paralled to the rolling direction in the tempered state.In this case, particulary the changes in microstructure, texture, crystal structure, lattice constant, electrical resistivity, mechanical hardness, Young’s modulus, internal stress were determined. By tempering at about 300°C after cold-working, the gamma phase appears first. The texture of the tempered state is very similar to that of the cold worked state. The former is the sharper. The investigation of the phase by X-rays is indentical to the observation by electron microscope. The lattice constant decreases first by tempering at about 300°C. The electrical resistivity reaches a maximum by tempering at 300°∼400°C and then a minimum by tempering at about 600°C.The mechanical hardness reaches the maximum by tempering at about 500°C. The internal stress reaches a minimum by tempering at about 400°C and then a maximum by tempering at 500°∼600°C. These are caused by the ordering of the alpha phase and the transformation of the alpha phase to the gamma phase by tempering. The magnetic anisotropy of Cr-containing Vicalloy is not caused by the directional order, but probably by the variation of the direction of easy magnetization during the ordering of the alpha phase by tempering. The coercive force of about 300 Oe is not only caused by a single domain but also by the difficulty of the domain wall displacement.The above-mentioned conception differs from the various theories in the past.