Patent ID: 10256017

Abstract:
A rare earth based permanent magnet formed by a sintered compact with an R-T-B based composition, wherein, R contains R1 and R2 as the necessity, R1 represents at least one rare earth element including Y and excluding Dy, Tb and Ho, and R2 represents at least one from the group made of Dy, Tb and Ho. Its main phase grains have a core-shell structure in which a core part and shell part coating the core part are contained. When the atom concentrations of R1 and R2 in the core part and the atom concentrations of R1 and R2 in the shell part are defined as αR1, αR2, βR1 and βR2, respectively, αR1<βR1, αR2>βR2, αR1<αR2 and βR2<βR1. Relative to all the main phase grains observed at the cross-section of the sintered compact, the ratio occupied by the main phase grain having the core-shell structure is 5% or more.