R-FE-B TYPE RARE EARTH SINTERED MAGNET AND PROCESS FOR PRODUCTION OF THE SAME

摘要

In an R-Fe-B based rare-earth sintered magnet according to the present invention, at a depth of 20 µm under the surface of its magnet body, crystal grains of an R 2 Fe 14 B type compound have an (RL 1-x RH x ) 2 Fe 14 B (where 0.2‰¦x‰¦0.75) layer with a thickness of 1 nm to 2 µm in their outer periphery. In this case, the light rare-earth element RL is at least one of Nd and Pr, and the heavy rare-earth element RH is at least one element selected from the group consisting of Dy, Ho and Tb.