Rare earth magnet

Patent metadata

Field	Value
Publication number	US-10325704-B2
Application number	US-201615380079-A
Country	US
Kind code	B2
Filing date	Dec 15, 2016
Priority date	Dec 18, 2015
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

A rare earth magnet having a main phase and a sub-phase, wherein the main phase has a ThMn12-type crystal structure; the sub-phase contains at least any one of an Sm5Fe17-based phase, an SmCo5-based phase, an Sm2O3-based phase, and an Sm7Cu3-based phase; assuming that the volume of the rare earth magnet is 100%, the volume fraction of the sub-phase is from 2.3 to 9.5% and the volume fraction of an α-Fe phase is 9.0% or less; and the density of the rare earth magnet is 7.0 g/cm3 or more.

First claim

The invention claimed is:

1. A rare earth magnet comprising a main phase and a sub-phase,
wherein the main phase has a ThMn 12 -type crystal structure,
wherein the sub-phase contains at least any one of an Sm 5 Fe 17 -based phase, an SmCo 5 -based phase, an Sm 2 O 3 -based phase, and an Sm 7 Cu 3 -based phase,
wherein the volume fraction of the sub-phase is from 2.3 to 9.5% and the volume fraction of an α-Fe phase is 9.0% or less, when the volume of the rare earth magnet is 100%, and
wherein the density of the rare earth magnet is 7.0 g/cm 3 or more.

2. The rare earth magnet according to claim 1 , wherein part of Fe of the Sm 5 Fe 17 -based phase is replaced by Ti.

3. The rare earth magnet according to claim 2 , wherein the Sm 5 Fe 17 -based phase contains an Sm 5 (Fe 0.95 Ti 0.05 ) 17 phase.

4. The rare earth magnet according to claim 1 , wherein part of Co of the SmCo 5 -based phase is replaced by Cu.

5. The rare earth magnet according to claim 4 , wherein the SmCo 5 -based phase contains an Sm(Co 0.3 Cu 0.2 ) 5 phase.

6. The rare earth magnet according to claim 1 , wherein the composition of the main phase is represented by the formula:
(R 1 (1-x) R 2 x ) a (Fe (1-y) Co y ) b T c M d

(wherein
R 1 is one or more rare earth elements selected from the group consisting of Sm, Pm, Er, Tm and Yb,
R 2 is one or more elements selected from the group consisting of Zr, La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho and Lu,
T is one or more elements selected from the group consisting of Ti, V, Mo, Si, Al, Cr and W,
M is one or more elements selected from the group consisting of Cu, Ga, Ag and Au, and unavoidable impurity elements,
0≤ x≤ 0.5,

0≤ y≤ 0.8,

4.0≤ a≤ 9.0,

b= 100− a−c−d,

3.0≤ c≤ 7.0, and

0≤ d≤ 3.0).

7. The rare earth magnet according to claim 1 , wherein the Sm 5 Fe 17 -phase, the SmCo 5 -phase, the Sm 2 O 3 -phase, and the Sm 7 Cu 3 -phase contain an Sm 5 Fe 17 phase, an SmCo 5 phase, an Sm 2 O 3 phase, and an Sm 7 Cu 3 phase, respectively.

8. The rare earth magnet according to claim 7 , wherein the Sm 7 Cu 3 -based phase contains a phase having mixed therein an Sm phase and an SmCu phase in a ratio of 3:4.

9. The rare earth magnet according to claim 8 , wherein the Sm phase contains a crystal phase and an amorphous Sm phase.

Assignees

• Toyota Motor Co Ltd

Inventors

• Sakuma Noritsugu
• Kato Akira
• Yano Masao
• Suzuki Shunji
• Kobayashi Kurima

Classifications

• C22C38/005 Primary

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

• H01F1/053 Primary

  containing rare earth metals · CPC title

• C22C38/10

  containing cobalt · CPC title

• C22C38/12

  containing tungsten, tantalum, molybdenum, vanadium, or niobium · CPC title

• C22C38/14

  containing titanium or zirconium · CPC title