PROCESS FOR PRODUCING RARE EARTH PERMANENT MAGNET MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a process for producing the material of a rare earth permanent magnet as an R1-Fe-B based anisotropic sintered magnet where magnetic characteristics impaired by grinding are recovered.

SOLUTION: An anisotropic sintered magnet body represented by composition formula R1x(Fe1-yCoy)100-x-z-aBzMa(R1is one kind or more than one kinds selected from rare earth elements inculding Sc and Y, M is one kind or more than one kinds selected from Al, Cu, Zn, In, Si, P, S, Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta and W, and x, y, z and a are atomic ratios in percent satisfying following relations; 10≤x≤15, 0≤y≤0.4, 3≤z≤15, 0≤a≤11) is ground to have a specific surface area of 6 mm-1or above. Subsequently, disproportionation reaction is caused in an R12Fe14B type compound of main phase by heat treatment in an atmosphere containing hydrogen gas, and recombination reaction on that compound is caused, thus making the crystal grain of that compound phase as fine as 1 μm or less. Thereafter, under such a state as containing one kind or more than one kinds selected from an oxide of R2, a fluoride of R3, and an acid fluoride of R4(R2, R3and R4are one kind or more than one kinds selected from rare earth elements including Sc and Y) with powder having an average particle size of 100 μm or less existing on the surface of a processed magnet, the magnet and powder are heat treated and the R2, R3and R4are absorbed to the magnet.

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