Magnetic powder, magnet, method for producing magnetic powder, and method for producing magnet

Patent metadata

Field	Value
Publication number	US-2026011473-A1
Application number	US-202519322890-A
Country	US
Kind code	A1
Filing date	Sep 9, 2025
Priority date	Mar 28, 2023
Publication date	Jan 8, 2026
Grant date	—

Abstract

A Sm—Fe—N-based magnetic material that includes: a main phase including a plurality of Sm—Fe—N-based crystal grains; and a grain boundary phase present between adjacent Sm—Fe—N-based crystal grains of the plurality of Sm—Fe—N-based crystal grains, and the grain boundary phase contains N, in which a ratio of a first content of N in the main phase to a second content of N in the grain boundary phase is 0.84 or more on an atomic basis.

First claim

1 . A Sm—Fe—N-based magnetic material comprising:
a main phase including a plurality of Sm—Fe—N-based crystal grains; and
a grain boundary phase present between adjacent Sm—Fe—N-based crystal grains of the plurality of Sm—Fe—N-based crystal grains, and the grain boundary phase contains N, wherein
a ratio of a first content of N in the main phase to a second content of N in the grain boundary phase is 0.84 or more on an atomic basis.

2 . The Sm—Fe—N-based magnetic material according to claim 1 , wherein
a content of Sm is 7.0 atom % to 11.5 atom % in a total of 100 atom % of all elements included in the Sm—Fe—N-based magnetic material,
a content of Fe is 61.5 atom % to 78.5 atom % in the total of 100 atom % of all elements included in the Sm—Fe—N-based magnetic material,
a content of Co is 0 atom % to 9.0 atom % in a total of 100 atom % of the elements included in the main phase,
a content of M1 that is one or more elements selected from Ti, V, Cr, Mn, Zr, Nb, Hf, Ta, and Si is 1.0 atom % to 4.0 atom % in the total of 100 atom % of all elements included in the Sm—Fe—N-based magnetic material,
a content of M2 that is one or more elements selected from B and C is 0 atom % to 2.5 atom % in the total of 100 atom % of all elements included in the Sm—Fe—N-based magnetic material, and
a content of the N is 12.0 atom % to 18.0 atom % in the total of 100 atom % of all elements included in the Sm—Fe—N-based magnetic material.

3 . The Sm—Fe—N-based magnetic material according to claim 1 , wherein a ratio of a content of the Fe to a content of the Sm is 5 to 11 on an atomic basis.

4 . The Sm—Fe—N-based magnetic material according to claim 1 , wherein a total content of the Sm and the Fe is 66.5 atom % to 90.0 atom % in 100 atom % of a total of the Sm—Fe—N-based magnetic powder.

5 . The Sm—Fe—N-based magnetic material according to claim 1 , wherein a content of Co in the Sm—Fe—N-based magnetic material is 0.0 atom % to 1.0 atom % in a total of 100 atom % of all elements included in the Sm—Fe—N-based magnetic material.

6 . The Sm—Fe—N-based magnetic material according to claim 1 , wherein the plurality of Sm—Fe—N-based crystal grains in the main phase includes one or more types selected from a Sm—Fe—N-based crystal exhibiting a Th 2 Zn 17 type structure and a Sm—Fe—N-based crystal exhibiting a TbCu 7 type structure.

7 . The Sm—Fe—N-based magnetic material according to claim 1 , wherein a content of N in the main phase is 5.5 atom % to 6.3 atom % in a total of 100 atom % of all elements included in the main phase.

8 . The Sm—Fe—N-based magnetic material according to claim 1 , wherein a crystallite diameter of the Sm—Fe—N-based crystal grain in the main phase is 10 nm to 1 μm.

9 . The Sm—Fe—N-based magnetic material according to claim 1 , wherein the grain boundary phase is a layer covering the Sm—Fe—N-based crystal grains.

10 . The Sm—Fe—N-based magnetic material according to claim 1 , wherein the grain boundary phase is a nonmagnetic phase.

11 . The Sm—Fe—N-based magnetic material according to claim 1 , wherein a content of N in the grain boundary phase is 6.0 atom % to 7.5 atom % in a total of 100 atom % of the main phase.

12 . The Sm—Fe—N-based magnetic material according to claim 1 , in a form of a magnetic powder or a magnet.

13 . A Sm—Fe—N-based magnet comprising:
the Sm—Fe—N-based magnetic powder according to claim 3 ; and
a binder.

14 . A method for producing a Sm—Fe—N-based magnetic material, the method comprising:
preparing a Sm—Fe-based crystalline material;
subjecting the Sm—Fe-based crystalline material to a nitriding treatment to produce a Sm—Fe—N-based precursor material; and
subjecting the Sm—Fe—N-based precursor material to a heat treatment at 400° C. to 500° C. in an atmosphere in which a concentration of N atoms and a concentration of 0 atoms are each 100 ppm or less, to produce the Sm—Fe—N-based magnetic material.

15 . The method according to claim 14 , wherein a step of cooling the Sm—Fe—N-based precursor material is not conducted between the nitriding treatment and the heat treatment.

16 . The method according to claim 14 , wherein, in the heat treatment, a heating time is 30 minutes to 600 minutes.

17 . A method for producing a Sm—Fe—N-based magnet, the method further comprising:
preparing a Sm—Fe-based crystalline material;
subjecting the Sm—Fe-based crystalline material to a nitriding treatment to produce a Sm—Fe—N-based precursor material;
subjecting the Sm—Fe—N-based precursor material to a heat treatment at 400° C. to 500° C. in an atmosphere in which a concentration of N atoms and a concentration of 0 atoms are each 100 ppm or less, to produce a Sm—Fe—N-based magnetic powder;
mixing the Sm—Fe—N-based magnetic powder and a raw material of a binder to produce a mixture; and
molding the mixture to produce the Sm—Fe—N-based magnet.

18 . The method according to claim 17 , wherein a step of cooling the Sm—Fe—N-based precursor material is not conducted between the nitriding treatment and the heat treatment.

19 . The method according to claim 17 , wherein, in the heat treatment, a heating time is 30 minutes to 600 minutes.

Assignees

• Murata Manufacturing Co

Inventors

• Sato Kazuki
• Takayama Kazuhiro
• Oga Satoshi

Classifications

• H01F41/0266

  Moulding; Pressing (H01F41/0273 takes precedence; hard magnetic particles H01F1/06, H01F1/11) · CPC title

• H01F7/02

  Permanent magnets {[PM]} · CPC title

• C23C8/80

  After-treatment · CPC title

• C23C8/26

  of ferrous surfaces · CPC title

• C22C2202/02

  Magnetic · CPC title