R-T-B BASED SINTERED MAGNET

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PROBLEM TO BE SOLVED : To provide an R-T-B based sintered magnet which is superior in the coercive force to an amount of use of a heavy rare earth element. SOLUTION : An R-T-B based sintered magnet comprises a first heavy rare earth element, where R includes Nd, T includes Co and Fe, and the first heavy rare earth element includes Tb or Dy. The R-T-B based sintered magnet has a region where the concentration of the first heavy rare earth element decreases from the surface toward the inside thereof. In a section including the region, there is a first grain boundary phase including the first heavy rare earth element and Nd with no Co included therein. Of the section including the region, the first grain boundary phase accounts for an area of 1.8% or less. SELECTED DRAWING : Figure 1 COPYRIGHT : (C)2018, JPO&INPIT