| 简介 |
A sintered R-T-B based magnet according to the present disclosure is a sintered R-T-B based magnet containing a main phase crystal grain and a grain boundary phase, the sintered R-T-B based magnet containing : R : not less than 27.5 mass% and not more than 35.0 mass% (R is at least one rare-earth element which always includes Nd and Pr); B : not less than 0.80 mass% and not more than 1.05 mass%; Ga : not less than 0.05 mass% and not more than 1.0 mass%; M : not less than 0 mass% and not more than 2 mass% (where M is at least one of Cu, Al, Nb and Zr); and a balance T (where T is Fe, or Fe and Co) and impurities. A Pr/Nd which is a ratio of a concentration of Pr to a concentration of Nd in a central portion of a main phase crystal grain that is located at a depth of 300 µm from the magnet surface is lower than 1; and a Pr/Nd which is a ratio of a concentration of Pr to a concentration of Nd in an intergranular grain boundary that is located at a depth of 300 µm from the magnet surface is higher than 1. A portion where the Ga concentration gradually decreases from the magnet surface toward the magnet interior exists. |
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