RARE EARTH SINTERED MAGNET AND PROCESS FOR PRODUCING THE SAME

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In a process of producing an R-Fe-B based rare-earth sintered magnet according to the present invention, first, an R-Fe-B based sintered magnet, including, as a main phase, R 2 Fe 14 B type compound crystal grains with a light rare-earth element RL (which is Nd and/or Pr) as a main rare-earth element R, is provided. Next, the surface of the sintered magnet body is coated with an RHM alloy layer including RH (which is at least one rare-earth element selected from Dy, Ho and Tb) and a metal M (which is at least one metallic element selected from Al, Cu, Co, Fe and Ag). Thereafter, a heat treatment is conducted at 500 °C to 1, 000 °C within a vacuum or an Ar atmosphere, thereby diffusing the metallic element M and the heavy rare-earth element RH inward from the surface of the rare-earth sintered magnet body.