MANUFACTURING METHOD OF RARE EARTH PERMANENT SINTERED MAGNET

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PROBLEM TO BE SOLVED : To provide a method of manufacturing a rare earth permanent sintered magnet for manufacturing a rare earth permanent sintered magnet having a large coercive force with a less amount of heavy rare earth element. SOLUTION : The rare earth permanent sintered magnet comprises a sintered material with a structure at least including a core forming a main phase, a shell around the core and/or a grain boundary phase. The core is formed of a low rare earth composition having a less amount ratio of the heavy rare earth element than that of the shell and/or the grain boundary phase, and the shell and/or the grain boundary phase is formed of a high rare earth composition having a higher amount ratio of the heavy rare earth element than that of the core. The method of manufacturing the rare earth permanent sintered magnet comprises the steps of obtaining a mixed material by mixing the particle of the high heavy rare earth composition and the particle of the low heavy rare earth composition, obtaining a molded material by molding the mixed material under the magnetic field, and sintering the molded material. In this method of manufacturing rare earth permanent sintered magnet, an average particle size of the particle of low heavy rare earth composition is 6 μm or less and the average particle size of the particle of the high heavy rare earth composition is smaller than the average particle size of the particle of the low heavy rare earth composition. COPYRIGHT : (C)2009, JPO&INPIT