Rare earth sintered magnet, method for manufacturing rare earth sintered magnet, rotor, and rotary machine

Abstract

A rare earth sintered magnet (1) comprises: a main phase (10) containing crystal grains satisfying the general formula (Nd, Pr, RH, R)-Fe-B and based on an Nd2Fe14B crystal structure, where RH denotes a heavy rare earth element containing at least one of Dy and Tb, and R denotes one or more rare earth elements selected from other than Nd, Pr, Dy, and Tb; and a subphase (20) present among a plurality of the main phases. The main phase has core sections (11c, 12c) and shell sections (11s, 12s) covering the core sections. The main phase has a first main phase (11) in which CNd > CPr and a second main phase (12) in which CNd < CPr, where CNd denotes the concentration of Nd in the core section and CPr denotes the concentration of Pr in the core section. The concentration of the heavy rare earth element RH in the core section of the first main phase is higher than the concentration of the heavy rare earth element RH in the core section of the second main phase. The first and second main phases are mixed and heavy rare earth elements are present on at least a part of the surfaces in the first main phase and the second main phase.