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

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PROBLEM TO BE SOLVED : To provide a method of manufacturing an R-T-B based sintered magnet in which a heavy rare earth element RH suppressing occurrence of crack and chip is diffused from the surface to the interior. SOLUTION : A method of manufacturing an R-T-B based sintered magnet includes a step of preparing an R-T-B based sintered magnet material 1, a step of preparing an RH diffusion source 2 containing a heavy rare earth element RH and Fe, a step of charging the sintered magnet material, RH diffusion source and a stirring auxiliary member 30 into a processing chamber 3 supported rotatably, and an RH diffusion step of heating the sintered magnet material and RH diffusion source to a treatment temperature of 800°C-1000°C, in the rotating processing chamber. Each sintered magnet material has a volume of 1000 mm3 or more, and the maximum size out of three sizes in three orthogonal directions is two times or more of the minimum size. Each RH diffusion source has a size of 3 mm or less. Each stirring auxiliary member includes a plurality of first spheres each having a diameter of 4-10 mm, and a plurality of second spheres each having a diameter of 1.5-3.5 mm. SELECTED DRAWING : Figure 2 COPYRIGHT : (C)2017, JPO&INPIT