METHOD OF PRODUCING R-T-B-BASED SINTERED MAGNET

To provide a method for producing an R-T-B based sintered magnet for obtaining a high Br and a high HcJ by reducing the content of a heavy rare earth element while inhibiting deterioration in pulverization efficiency at the time of jet mill pulverization even if the grinding grain size of a fine powder is reduced.SOLUTION: There is provided a method for producing an R-T-B based sintered magnet which comprises: a step of preparing an addition alloy powder containing 33 to 69 mass% of R1, 0.2 to 0.8 mass% of B, 0.8 to 3.0 mass% of Cu, 1.8 to 10 mass% of Ga, and 15 to 60 mass% of T; a step of preparing a main alloy powder containing 28.5 to 33.0 mass% of R, 0.80 to 1.0 mass% of B, 0.1 to 0.4 mass% of Ga, and 64 to 70 mass% of T; a step of preparing a mixed alloy powder; a step of supplying the mixed alloy powder to a jet mill device in which a pulverization chamber is filled with inert gas to perform pulverization to obtain a fine powder; and a step of producing a sintered body of the fine powder, in which the Pr content of the addition alloy powder is larger than the Pr content of the main alloy powder.SELECTED DRAWING: Figure 1 【課題】微粉末の粉砕粒度を低下させてもジェットミル粉砕時の粉砕効率の悪化を抑止しつつ、重希土類元素の含有量を低減して高いＢｒと高いＨｃＪを得るＲ−Ｔ−Ｂ系磁石の製造方法を提供する。【解決手段】Ｒ−Ｔ−Ｂ系焼結磁石の製造方法であって、Ｒ１：３３〜６９質量％、Ｂ：０．２〜０．８質量％、Ｃｕ：０．８〜３．０質量％、Ｇａ：１．８〜１０質量％、Ｔ：１５〜６０質量％、を含む添加合金粉末を準備する工程と、Ｒ：２８．５〜３３．０質量％、Ｂ：０．８０〜１．０質量％、Ｇａ：０．１〜０．４質量％、Ｔ：６４〜７０質量％、を含む主合金粉末を準備する工程と、混合合金粉末を準備する工程と、粉砕室が不活性ガスで満たされたジェットミル装置に混合合金粉末を供給して粉砕を行って微粉末を得る工程と、微粉末の焼結体を作製する工程とを含み、添加合金粉末のＰｒ含有量は主合金粉末のＰｒ含有量よりも多い。【選択図】図１