| 简介 |
PROBLEM TO BE SOLVED : To provide a sintered R-T-B rare earth permanent magnet in which a coercive force is increased, while a decline of the remanent magnetic flux density of the sintered magnet is restrained, and to provide a method of efficiently and certainly preparing the R-T-B rare earth permanent magnet.
SOLUTION : A R1-T-B sintered compact comprising a R12T14B compound as a major phase is brought in contact with a quenched alloy powder which is obtained by quenching a melt containing R2 (one or more elements selected from rare earth elements including Sc and Y) and M (one or more elements selected from B, C, P, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, Hf, Ta, W, Pt, Au, Pb, and Bi). The sintered compact and the alloy powder are heated in vacuum or an inert gas atmosphere at a temperature equal to or lower than the sintering temperature of the sintered compact for causing R2 element to diffuse into the sintered compact. As a result, coating a quenched alloy powder containing R2 and M onto a sintered compact and effecting diffusion treatment prevents oxidation of the powder and reduces hazard of handling. The R-T-B sintered magnet, which has excellent productivity and reduced amounts of expensive Tb and Dy used, can be prepared.
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