MATERIAL ALLOY FOR SINTERED MAGNET, RARE EARTH SINTERED MAGNET, AND METHOD FOR PRODUCING THEM

摘要

PROBLEM TO BE SOLVED: To provide a material alloy for a sintered magnet, capable of efficiently improving magnetic characteristics (specifically coercive force) of a rare earth sintered magnet while minimizing the usage of Dy.SOLUTION: A material alloy for a sintered magnet of the present invention has a metal structure including a main phase comprising crystal grains of a tetragonal compound (RFeB) of a first rare earth element (R), Fe and B and a grain boundary phase formed between the crystal grains, and is sintered to act as a rare earth sintered magnet. In the material alloy for a sintered magnet, a second rare earth element (R') capable of producing a tetragonal compound having an anisotropy magnetic field greater than that of the first rare earth element is concentrated higher in the grain boundary phase than in the main phase. The material alloy for a sintered magnet can be obtained by diffusing R' into a strip-casted R-Fe-B based magnet alloy foil.