Method of manufacturing magnetically anisotropic magnet materials and

Abstract

Disclosed are a method of and a device for manufacturing Nd-Fe-B alloy magnet materials, and in particular, for manufacturing an integral, columnar-ring-shaped Nd-Fe-B magnet which is multi-pole-magnetized along the circumference thereof and which is used as the rotor magnet of a high-efficiency stepping motor. According to the method, a green compact or a densified compact is first prepared from a selected flake or a powder material composed of amorphous and/or fine-crystallized particles obtained through rapid quenching of the molten alloy. It is then provided with magnetic anisotropy through plastic deformation effected radially inwardly along substantially the entire periphery of the compact initially deformed to receive a mandrel-core, and maintained at a temperature of 600 to 850 degrees C. Subsequently, the deformed body is magnetized with the desired radial or polar magnetization pattern. The device of this invention is composed of a die an upper punch, and a lower punch having two concentric sections. The space defined by the die and the upper and lower punches includes induction means for heating the green compact or the densified compact and sealing means for keeping the die under a reduced pressure condition or in an inert gas atmosphere.