Patent ID: 10242780

Abstract:
A rare earth based permanent magnet has a sintered compact with R-T-B based composition. The compact has two kinds of main phase grains M1 and M2 having different concentration distributions of R including R1 and R2 respectively representing at least one rare earth element including Y and excluding Dy, Tb and Ho, and at least one from Ho, Dy and Tb. M1 and M2 have a core-shell structure containing a shell part coating a core part. In M1, when the R1 and R2 atom concentrations in the core and shell parts are defined as αR1, αR2, βR1 and βR2, respectively, αR1>βR1, αR2<βR2, αR1>αR2 and βR1<βR2. In M2, when the R1 and R2 atom concentrations in the core and shell parts are defined as γR1, γR2, εR1 and εR2, respectively, γR1<εR1, γR2>εR2, γR1<γR2 and εR1>εR2. Ratios occupied by the main phase grains having the core-shell structure are 5% or more, respectively.