Rare earth magnet, method for manufacturing the same, and motor including the same

A method for manufacturing an R-T-B-based rare earth magnet in which R is a rare earth element, T is Fe and/or Co, and B is boron, the method comprising

• preparing a diffusion material penetrated rare earth magnet precursor having a magnet region layer and a surface layer covering a C-plane of the magnet region layer by diffusive penetration of a diffusion material into a rare earth magnet precursor;
• and
• manufacturing an R-T-B-based rare earth magnet by polishing the diffusion material penetrated rare earth magnet precursor,
• wherein in the preparing, the diffusion material is represented by Formula of R2(1-s)M2s (in the formula, R2 is one or more elements selected from the group consisting of Nd, Pr, Gd, Tb, Dy, Ce, La, and Ho, M2 is a metallic element other than rare earth elements and allowed to be alloyed with R2 and an unavoidable impurity elements, and (1-s) and s are molar ratios where 0.05≤s≤0.40), the diffusion material penetrated rare earth magnet precursor includes a main phase having an R2T14B-type crystal structure and a grain boundary phase present around the main phase, and the main phase has an average grain size from 1.0 μm to 10.0 μm, and
• wherein in the manufacturing, the surface layer present on the C-plane of the diffusion material penetrated rare earth magnet precursor is polished such that 85% or more of a total area of the C-plane of the diffusion material penetrated rare earth magnet precursor remains.

A method for manufacturing an R-T-B-based rare earth magnet in which R is a rare earth element, T is Fe and/or Co, and B is boron, the method comprising preparing a diffusion material penetrated rare earth magnet precursor having a magnet region layer and a surface layer covering a C-plane of the magnet region layer by diffusive penetration of a diffusion material into a rare earth magnet precursor;

• and
• manufacturing an R-T-B-based rare earth magnet by polishing the diffusion material penetrated rare earth magnet precursor,
• wherein in the preparing, the diffusion material is represented by Formula of R2(1-s)M2s (in the formula, R2 is one or more elements selected from the group consisting of Nd, Pr, Gd, Tb, Dy, Ce, La, and Ho, M2 is a metallic element other than rare earth elements and allowed to be alloyed with R2 and an unavoidable impurity elements, and (1-s) and s are molar ratios where 0.05≤s≤0.40), the diffusion material penetrated rare earth magnet precursor includes a main phase having an R2T14B-type crystal structure and a grain boundary phase present around the main phase, and the main phase has an average grain size from 1.0 μm to 10.0 μm, and
• wherein in the manufacturing, the diffusion material penetrated rare earth magnet precursor is polished to less than a thickness of the surface layer expressed by a following formula of use amount of the diffusion material (amount of diffusion material to a total weight of the rare earth magnet precursor (weight %))×2.2172.