Alloy for R-T-B-based rare earth sintered magnet, process of producing alloy for R-T-B-based rare earth sintered magnet, alloy material for R-T-B-based rare earth sintered magnet, R-T-B-based rare earth sintered magnet, process of producing R-T-B-based rare earth sintered magnet, and motor

Patent metadata

Field	Value
Publication number	US-11024448-B2
Application number	US-201615219110-A
Country	US
Kind code	B2
Filing date	Jul 25, 2016
Priority date	Jul 8, 2011
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

An alloy for R-T-B-based rare earth sintered magnets which contains R which is a rare earth element; T which is a transition metal essentially containing Fe; a metallic element M containing one or more metals selected from Al, Ga and Cu; B and inevitable impurities, in which R accounts for 13 at % to 15 at %, B accounts for 4.5 at % to 6.2 at %, M accounts for 0.1 at % to 2.4 at %, T accounts for balance, a proportion of Dy in all rare earth elements is in a range of 0 at % to 65 at %, and the following Formula 1 is satisfied,

0.0049Dy+0.34≤B/TRE≤0.0049Dy+0.36  Formula 1

wherein Dy represents a concentration (at %) of a Dy element, B represents a concentration (at %) of a boron element, and TRE represents a concentration (at %) of all the rare earth elements.

First claim

What is claimed is:

1. An R-T-B-based rare earth sintered magnet comprising:
R which is a rare earth element except for Dy and Tb;
T which is a transition metal essentially comprising Fe;
a metallic element M comprising Ga, or
comprising Ga and one or more metals selected from the group consisting of Al and Cu;

B; and
inevitable impurities,
wherein the R-T-B-based rare earth sintered magnet does not contain Dy and Tb,
wherein R accounts for 13 at % to 15 at %, B accounts for 5.06 at % to 5.34 at %, M accounts for 0.1 at % to 2.4 at %, Si accounts for 0.09 at % or less, T accounts for the balance, and the following Formula 1 is satisfied,
0.34≤cB/TRE≤0.36  Formula 1

wherein cB represents a concentration at % of a boron element, and TRE represents a concentration at % of all the rare earth elements:

wherein the R-T-B-based rare earth sintered magnet is made of a sintered body including a main phase primarily comprising R 2 Fe 14 B and a grain boundary comprising more R than the main phase, in which the grain boundary phase includes a phase having a concentration of all atoms of the rare earth elements of 70 at % or more and a phase having a concentration of all the atoms of the rare earth elements in a range of 25 at % to 35 at %; and
wherein Ga accounts for 0.24 at % to 1.95 at % but at least 0.52 wt % in the R-T-B-based rare earth sintered magnet.

2. The R-T-B-based rare earth sintered magnet according to claim 1 ,
wherein a volume ratio of the phase having a concentration of all the atoms of the rare earth elements in a range of 25 at % to 35 at % is in a range of 0.005 vol. % to 3 vol. %.

3. A motor including the R-T-B-based rare earth sintered magnet according to claim 1 .

4. The R-T-B-based rare earth sintered magnet according to claim 1 ,
further comprising Nd,
wherein an amount of Nd is 70 at % or more among the rare earth elements R.

5. The R-T-B-based rare earth sintered magnet according to claim 1 ,
further comprising Nd,
wherein an amount of Nd is 75 at % or more among the rare earth elements R.

6. The R-T-B-based rare earth sintered magnet according to claim 1 , wherein Ga accounts for 0.49 at % to 0.54 at % in the R-T-B based rare earth sintered magnet.

Assignees

• Tdk Corp

Inventors

• Nakajima Kenichiro
• Yamazaki Takashi

Classifications

• B22F3/24 Primary

  After-treatment of workpieces or articles {(B22F3/1146 takes precedence)} · CPC title

• H01F1/058

  and IVa elements, e.g. Gd2Fe14C · CPC title

• H01F1/0577

  sintered · CPC title

• C22C38/10

  containing cobalt · CPC title

• H01F41/0293

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