R-Fe-B RARE-EARTH SINTERED MAGNET AND PROCESS FOR PRODUCING THE SAME

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An R-Fe-B rare-earth sintered magnetic object is prepared which has, as the main phase, R2Fe14B type compound crystal grains containing a light rare-earth element (RL) (at least either of Nd and Pr) as the main rare-earth element (R). Subsequently, an M layer comprising one or more metallic elements (M) (M is at least one member selected from the group consisting of Al, Ga, In, Sn, Pb, Bi, Zn, and Ag) is deposited on the surface of the sintered magnetic object. An RH layer comprising one or more heavy rare-earth elements (RH) (at least one member selected from the group consisting of Dy, Ho, and Tb) is then deposited on the M layer. Thereafter, the resultant sintered magnetic object is heated to diffuse the metallic elements (M) from the surface into inner parts of the sintered magnet and diffuse the heavy rare-earth elements (RH) from the surface into inner parts of the sintered magnet.