METHOD FOR PRODUCING POWDER COMPACT FOR MAGNET, POWDER COMPACT FOR MAGNET, AND SINTERED BODY

摘要

Provided are: a method for producing, with high productivity, a powder compact that can be used to obtain a rare-earth sintered magnet with superior magnet properties; a powder compact for magnet application that exhibits superior orientation and is suitable as a raw material for a rare-earth sintered magnet; and a sintered body. Base powders (P) are put into a forming mold (50), pressurized/compressed, and exposed to magnetic fields in order to form the powder compact, said base powders comprising a rare-earth alloy and containing 15% by mass or more of fine particles having a grain size equal to or smaller than 2µm. A compact (10), which has been formed by applying a weak magnetic field of 1T-2T to a powder compact packed at a packing density resulting in a bulk density of 1.05-1.2, is excited, by means of a superconducting coil (60), to 3T or higher at an excitation rate between 0.01T/sec and 0.15T/sec in order to apply a strong magnetic field of 3T or higher to the compact. The superconducting coil (60) applies the magnetic field in the opposite direction to the direction of a magnetic field applied by a normal conducting coil (70), and high-speed excitation is carried out so as to rotate fine particles as well as coarse particles in order to improve the orientation.