METHOD FOR MANUFACTURING R-T-B BASED SINTERED MAGNET

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PROBLEM TO BE SOLVED : To provide a method for manufacturing an R-T-B based sintered magnet having a high coercive force HcJ. SOLUTION : A method for manufacturing an R-T-B based sintered magnet including 28.5-33.5 mass% of a rare earth element including at least one kind of Nd and Pr, 0.84-0.92 mass% of B, 0.3-0.7 mass% of Ga, 0.05-0.35 mass% of Cu, 0.02-0.50 mass% of Al, and 61.0 mass% or more of Fe+Co, and satisfying an expression given by 14[B]/10.8<[Fe+Co]/55.85 comprises the steps of : heating at least one or more kinds of R-Ga alloys in a hydrogen atmosphere at a temperature of 200-450°C to obtain a hydrogen-occluding R-Ga alloy; mixing the hydrogen-occluding R-Ga alloy with one or more kinds of primary alloys to obtain a mixed alloy powder; molding and sintering the resultant mixture alloy; and performing a thermal treatment on the resultant mixture alloy. In the step of obtaining the mixed alloy powder, the hydrogen-occluding R-Ga alloy is pulverized with hydrogen occluded by the alloy, and the mass ratio of the R-Ga alloy powder to a mass of the mixed alloy powder is 1-5%. SELECTED DRAWING : Figure 1A COPYRIGHT : (C)2018, JPO&INPIT