Rare earth magnet and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-12502709-B2
Application number	US-202117545245-A
Country	US
Kind code	B2
Filing date	Dec 8, 2021
Priority date	Dec 28, 2020
Publication date	Dec 23, 2025
Grant date	Dec 23, 2025

Abstract

Provided is a rare earth magnet that allows suppressing deterioration of magnetic properties and a method for manufacturing the same. The rare earth magnet of the present disclosure includes a magnet body containing a rare earth element R1, a transition metal element T, and boron B and includes a main phase. A region in the vicinity of a corner portion of the magnet body of a constituent surface constituting a surface of the magnet body is a processed surface on which a removal process has been performed, and a region closer to a center than the region in the vicinity of the corner portion of the constituent surface is a non-processed surface on which the removal process is not performed.

First claim

What is claimed is:

1 . A rare earth magnet comprising:
a magnet body containing a rare earth element R1, a transition metal element T, and boron B, and a rare-earth-rich layer, wherein the magnet body is composed of a sintered body including main phase particles and subphases that are present surrounding main phase particles, wherein the shape of the magnet body is a rectangular parallelepiped whose constituent surfaces are six rectangular constituent surfaces, wherein a corner region in each of the six rectangular constituent surfaces of the magnet body is an exposed surface of the inside of the sintered body where the subphases are removed and the surface regions of the main phase particles are exposed, wherein the corner region is at a part where at least two rectangular constituent surfaces among the six rectangular constituent surfaces of the magnet body intersect, wherein the at least two rectangular constituent surfaces perpendicularly intersect with each other, wherein a center region closer to a center than the corner region in each of the six rectangular constituent surfaces of the magnet body is an outer surface of the sintered body where the inside of the sintered body is not exposed, wherein the rare-earth-rich layer is disposed on the corner region in each of the six rectangular constituent surfaces of the magnet body, and the rare-earth-rich layer is not disposed on the center region in each of the six rectangular constituent surfaces of the magnet body, wherein the rare-earth-rich layer is a layer which is richer in a rare earth element R2 than a surface part of the corner region in each of the six rectangular constituent surfaces of the magnet body, wherein a diffusion layer is disposed on the surface part of the corner region in each of the six rectangular constituent surfaces of the magnet body, wherein the diffusion layer is a layer in which the rare earth element R2 is diffused into the surface part of the corner region in each of the six rectangular constituent surfaces of the magnet body and is a layer which is richer in the rare earth element R2 than the inside of the magnet body, and wherein the rare earth element R2 contains one or two selected from Dy and Tb.

Assignees

• Toyota Motor Co Ltd

Inventors

• Takazawa Mayumi
• Haga Kazuaki
• Ichigozaki Daisuke
• Ito Masaaki
• Koma Hisanori
• Sano Shinya
• Komori Kensuke
• Kanada Keiu

Classifications

• H01F41/0293 Primary

  diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets · CPC title

• H01F41/0286

  Trimming · CPC title

• B22F2003/248

  Thermal after-treatment · CPC title

• B22F2003/247

  Removing material: carving, cleaning, grinding, hobbing, honing, lapping, polishing, milling, shaving, skiving, turning the surface · CPC title

• B22F3/16

  in successive or repeated steps · CPC title