R-T-B-based rare earth magnet particles, process for producing the R-T-B-based rare earth magnet particles, and bonded magnet

Patent metadata

Field	Value
Publication number	US-12562297-B2
Application number	US-202117399333-A
Country	US
Kind code	B2
Filing date	Aug 11, 2021
Priority date	Mar 13, 2013
Publication date	Feb 24, 2026
Grant date	Feb 24, 2026

Abstract

An object of the present invention is to enhance a coercive force of magnetic particles by promoting formation of a continuous R-rich grain boundary phase in a crystal grain boundary of a magnetic phase of the particles, and to thereby obtain R-T-B-based rare earth magnet particles further having a high residual magnetic flux density. The present invention relates to production of R-T-B-based rare earth magnet particles capable of exhibiting a high coercive force even when a content of Al therein is reduced, and a high residual magnetic flux density, in which formation of an R-rich grain boundary phase therein can be promoted by heat-treating Al-containing R-T-B-based rare earth magnet particles obtained by HDDR treatment in vacuum or in an Ar atmosphere at a temperature of not lower than 670° C. and not higher than 820° C. for a period of not less than 30 min and not more than 300 min.

First claim

What is claimed is:

1 . A process for producing R-T-B-based rare earth magnet particles, comprising steps of:
subjecting a raw material alloy comprising: R, wherein R represents at least one rare earth element including Y, T, wherein T represents Fe, or Fe and Co, B, wherein B represents boron, and Al, wherein Al represents aluminum, to HDDR treatment to obtain Al-containing R-T-B-based rare earth magnet particles having an Al content of more than 0 atom % and not more than 1.0 atom %; and
heat-treating the Al-containing R-T-B-based rare earth magnet particles in vacuum or in an Ar atmosphere at a temperature of not lower than 670° C. and not higher than 820° C. for a period of not less than 30 min and not more than 300 min,
wherein the R-T-B-based rare earth magnet particles do not comprise Nb, wherein the R-T-B-based rare earth magnet particles have a coercive force of not less than 1290 kA/m, and wherein the R-T-B-based rare earth magnet particles have a residual magnetic flux density of not less than 1.25 T.

2 . The process for producing R-T-B-based rare earth magnet particles according to claim 1 , wherein the raw material alloy has a composition comprising R in an amount of not less than 12.5 atom % and not more than 14.3 atom %, and B in an amount of not less than 4.5 atom % and not more than 7.5 atom %.

3 . The process for producing R-T-B-based rare earth magnet particles according to claim 1 , wherein the raw material alloy comprises Ga and Zr, and has a composition comprising Co in an amount of not more than 10.0 atom %, Ga in an amount of not less than 0.1 atom % and not more than 1.0 atom % and Zr in an amount of not less than 0.05 atom % and not more than 0.15 atom %.

4 . The process for producing R-T-B-based rare earth magnet particles according to claim 1 , wherein R represents at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb and Lu.

5 . The process for producing R-T-B-based rare earth magnet particles according to claim 1 , wherein the R-T-B-based rare earth magnet particles do not comprise Dy.

Assignees

• Toda Kogyo Corp

Inventors

• Katayama Nobuhiro
• Kawasaki Hirofumi
• Morimoto Koichiro

Classifications

• C22C38/14

  containing titanium or zirconium · CPC title

• C22C38/10

  containing cobalt · CPC title

• C22C38/005

  containing rare earths, i.e. Sc, Y, Lanthanides · CPC title

• C22C2202/02

  Magnetic · CPC title

• B22F2999/00

  Aspects linked to processes or compositions used in powder metallurgy · CPC title