RFeB-BASED SINTERED MAGNET PRODUCTION METHOD AND RFeB-BASED SINTERED MAGNETS

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A method for producing RFeB system sintered magnet composed of at least two unit sintered magnets bonded to each other at flat bonding surfaces, each unit sintered magnet composed of crystal grains whose main phase is made of R2Fe14B containing, as a main rare-earth element R, light rare-earth element RL wherein at least one element selected from the group of Nd and Pr. Paste prepared by mixing organic matter and metallic powder containing at least one element selected from heavy rare-earth elements RH of Dy, Ho and Tb is sandwiched between neighboring unit sintered magnets, and a grain boundary diffusion treatment is performed. Coercivity is improved by this grain boundary diffusion treatment. Since an oxide or similar compound of RH and/or RL is formed at boundary of unit sintered magnets, the influence of eddy current during a period of use is suppressed, and unit sintered magnets are strongly bonded together.