R-t-b based sintered magnet and rotating machine

Patent metadata

Field	Value
Publication number	US-10256015-B2
Application number	US-201414906682-A
Country	US
Kind code	B2
Filing date	Aug 8, 2014
Priority date	Aug 9, 2013
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

The present invention provides an R-T-B based sintered magnet having excellent corrosion resistance together with good magnetic properties. The R-T-B based sintered magnet contains R2T14B crystal grains, wherein, an R—Ga—Co—Cu—N concentrated part exists in a grain boundary formed between or among two or more adjacent R2T14B crystal grains, and the concentrations of R, Ga, Co, Cu and N in the R—Ga—Co—Cu—N concentrated part are higher than those in the R2T14B crystal grains respectively.

First claim

What is claimed is:

1. An R-T-B based sintered magnet comprising
R 2 T 14 B crystal grains, and a grain boundary formed between or among two or more adjacent R 2 T 14 B crystal grains,
Ga in an amount in a range of from 0.1 mass % to 1.0 mass %,
Co in an amount in a range of from 0.3 mass % to 3.0 mass %,
Cu in an amount in a range of from 0.05 mass % to 1.5 mass %,
N, and
Zr in an amount in a range of from 0.01 mass % to 1.5 mass %, wherein
R represents at least one rare earth element and a content of R in the R-T-B based sintered magnet is in a range of from 29.5 mass % to 33 mass %,
T represents one or more transition metal elements comprising Fe or a combination of Fe and Co,
a content of B in the R-T-B based sintered magnet is in a range of from 0.75mass % to 0.95 mass %,
the grain boundary contains R—Ga—Co—Cu—N concentrated parts, each of which is a single, continuous area within the grain boundary in which concentrations of R, Ga, Co, Cu, and N are higher than those in the R 2 T 14 B crystal grains respectively,
the R—Ga—Co—Cu—N concentrated parts are separate from an R-—rich phase in the grain boundary,
a number of Ga atoms in the R—Ga—Co—Cu—N concentrated part is in a range of from 7 to 16% of a total atom number of R, Fe, Ga, Co, Cu, and N,
a number of Co atoms in the R—Ga—Co—Cu—N concentrated part is in a range of from 1 to 9% of a total atom number of R, Fe, Ga, Co, Cu, and N,
a number of Cu atoms in the R—Ga—Co—Cu—N concentrated part is in a range of from 4 to 8% of a total atom number of R, Fe, Ga, Co, Cu, and N, and
a number of N atoms in the R—Ga—Co—Cu—N concentrated part is in a range of from 1 to 13% of a total atom number of R, Fe, Ga, Co, Cu, and N.

2. A rotating machine comprising the R-T-B based sintered magnet of claim 1 .

Assignees

• Tdk Corp

Inventors

• Miwa Masashi
• Nakajima Haruna
• Kanada Isao

Classifications

• H01F1/0536 Primary

  sintered · CPC title

• H01F1/0577 Primary

  sintered · CPC title

• H01F41/0293

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