Rare earth magnet

Patent metadata

Field	Value
Publication number	US-10991493-B2
Application number	US-201615560907-A
Country	US
Kind code	B2
Filing date	Mar 25, 2016
Priority date	Mar 25, 2015
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

A rare earth magnet includes main phase grains having an R 2 T 14 B type crystal structure. The main phase grains include Ga. A concentration ratio A (A=αGa/βGa) of the main phase grains is 1.20 or more, where αGa and βGa are respectively a highest concentration of Ga and a lowest concentration of Ga in one main phase grain.

First claim

The invention claimed is:

1. A rare earth magnet comprising main phase grains having an R 2 T 14 B type crystal structure, and comprising
R: 29.5 to 35.0 mass %; B: 0.87 to 0.98 mass %; M: 0.03 to 1.7 mass %; Cu: 0.01 to 1.5 mass %; Fe: substantial remaining part; total content of element(s) other than Fe occupying the remaining part: 5.0 mass % or less,
wherein M is Ga: 0.03 to 1.5 mass %; and one or more elements selected from the group consisting of Al, Si, Ge and Sn, and
wherein
an atom concentration ratio A (A=αGa/βGa) of the main phase grains is 1.50 or more, where αGa and βGa are respectively a highest concentration of Ga and a lowest concentration of Ga in one main phase grain, and
an absolute value of thermal demagnetization factor is 0.5% or less.

2. The rare earth magnet according to claim 1 , wherein a position showing βGa is located within 100 nm from an edge part of the main phase grain toward an inner part of the main phase grain.

3. The rare earth magnet according to claim 1 ,
wherein
the main phase grain comprises a concentration gradient of Ga increasing from an edge part of the main phase grain toward an inner part of the main phase grain, and
a region with the concentration gradient of Ga has a length of 100 nm or more.

4. The rare earth magnet according to claim 1 ,
wherein
the main phase grain comprises a concentration gradient of Ga increasing from an edge part of the main phase grain toward an inner part of the main phase grain, and
a region whose absolute value of the concentration gradient of Ga is 0.05 atom %/μm or more has a length of 100 nm or more.

5. The rare earth magnet according to claim 1 ,
wherein
0.05 atom % or more of C is detected in all main phase grains in an area 100 nm or more from an edge part of each main phase grain toward an inner part of each main phase grain.

6. The rare earth magnet according to claim 1 , wherein R includes both Nd and Pr, and each of a ratio of Nd in R and a ratio of Pr in R is 10 mass % or more.

7. The rare earth magnet according to claim 1 ,
wherein
a relation of 1.20<[M]/[C]<2.00 is satisfied, where [C] and [M] are the number of atoms of C and M elements present in the magnet.

8. The rare earth magnet according to claim 2 ,
wherein
the main phase grain comprises a concentration gradient of Ga increasing from an edge part of the main phase grain toward an inner part of the main phase grain, and
a region with the concentration gradient of Ga has a length of 100 nm or more.

9. The rare earth magnet according to claim 2 ,
wherein
the main phase grain comprises a concentration gradient of Ga increasing from an edge part of the main phase grain toward an inner part of the main phase grain, and
a region whose absolute value of the concentration gradient of Ga is 0.05 atom %/μm or more has a length of 100 nm or more.

10. The rare earth magnet according to claim 3 ,
wherein
the main phase grain comprises a concentration gradient of Ga increasing from an edge part of the main phase grain toward an inner part of the main phase grain, and
a region whose absolute value of the concentration gradient of Ga is 0.05 atom %/μm or more has a length of 100 nm or more.

11. The rare earth magnet according to claim 8 ,
wherein
the main phase grain comprises a concentration gradient of Ga increasing from an edge part of the main phase grain toward an inner part of the main phase grain, and
a region whose absolute value of the concentration gradient of Ga is 0.05 atom %/μm or more has a length of 100 nm or more.

Assignees

• Tdk Corp

Inventors

• Okawa Wakako
• Goto Syota
• Fujikawa Yoshinori

Classifications

• C22C28/00 Primary

  Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00 · CPC title

• B22F3/00

  Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor {; Presses and furnaces} · CPC title

• H01F1/0577 Primary

  sintered · CPC title

• B22F2009/044

  by jet milling · CPC title

• H01F1/08

  pressed, sintered, or bound together · CPC title