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

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The present invention addresses the problem of providing a method for producing an RFeB system sintered magnet with high corrosion resistance and low loss of energy in an RFeB system sintered magnet with high magnetic properties produced by a grain boundary diffusion process. A paste 12 prepared by mixing an organic matter having a molecular structure including an oxygen atom and a metallic powder containing a heavy rare-earth element RH which is at least one element selected from the group of Dy, Ho and Tb, is applied to the surface of an RFeB system sintered compact 11 composed of crystal grains whose main phase is R2Fe14B containing, as a main rare-earth element R, a light rare-earth element RL which is at least one element selected from the group of Nd and Pr. A heating process for a grain boundary diffusion treatment is performed, with the paste in contact with the surface. As a result, a protective layer 13 containing an oxide of the light rare-earth element RL is formed on the surface. This protective layer 13 is highly corrosion resistant. Furthermore, its high electric resistivity suppresses an occurrence of eddy current and thereby contributes to decreasing the loss of energy.