| 简介 |
PROBLEM TO BE SOLVED : To provide an R-T-B-based magnet having a large coercive force without increasing a Dy content.
SOLUTION : An R-T-B-based rare earth sintered magnet comprises : R consisting of rare earth elements; T consisting of transition metals including Fe as an essential element; Al and/or Ga, as a metal element M; B; Cu; and inevitable impurities. The R-T-B-based rare earth sintered magnet includes 14.5-15 atom% of R, 4.5-5.5 atom% of B and 0.1-2.0 atom% of M with the balance consisting of T; the content of Dy in all the rare earth elements is 0-65 atom%. The R-T-B-based rare earth sintered magnet is composed of a sintered compact having a main phase including R2Fe14B mainly and a grain boundary phase including more R than the main phase. The grain boundary phase includes : an R-rich phase having a total atomic concentration of 70 atom% or more for the rare earth elements; and a ferromagnetic transition metal-rich phase having a total atomic concentration of 25-35 atom% for the rare earth elements. In the grain boundary phase, the areal percentage of the transition metal-rich phase is 40% or more.
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