	US 12,322,542 B2
	Rare earth magnet and production method thereof
Masaaki Ito, Anjo (JP); Reimi Tabuchi, Nisshin (JP); Motoki Hiraoka, Toyota (JP); and Hisashi Maehara, Itano-gun (JP)
Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP); and NICHIA CORPORATION, Anan (JP)
Filed by TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP); and NICHIA CORPORATION, Anan (JP)
Filed on Nov. 14, 2022, as Appl. No. 17/986,179.
Claims priority of application No. 2021-190550 (JP), filed on Nov. 24, 2021.
Prior Publication US 2023/0162913 A1, May 25, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H01F 41/02 (2006.01); B22F 1/00 (2022.01); B22F 3/16 (2006.01); B22F 3/24 (2006.01); C22C 38/00 (2006.01); H01F 1/059 (2006.01)

CPC H01F 41/0266 (2013.01) [B22F 1/09 (2022.01); B22F 3/16 (2013.01); B22F 3/24 (2013.01); C22C 38/001 (2013.01); C22C 38/005 (2013.01); H01F 1/059 (2013.01); H01F 1/0596 (2013.01); H01F 41/0253 (2013.01); H01F 41/0273 (2013.01); B22F 2003/248 (2013.01); B22F 2301/355 (2013.01); B22F 2304/10 (2013.01); C22C 2202/02 (2013.01)]

6 Claims

1. A production method of a rare earth magnet, comprising:

preparing a magnetic powder having a magnetic phase which contains Sm, Fe and N and at least partially has a crystal structure of either Th₂Zn₁₇type or Th₂Ni₁₇type,

preparing a modifier powder containing at least either a metallic zinc or a zinc alloy,

mixing the magnetic powder and the modifier powder to obtain a mixed powder,

compression-molding the mixed powder in a magnetic field to obtain a magnetic-field molded body,

pressure-sintering the magnetic-field molded body to obtain a sintered body, and

heat-treating the sintered body, wherein

D₅₀of the magnetic powder is 1.50 μm or more and 3.00 μm or less,

the content ratio of the zinc component in the modifier powder is 6 mass % or more and 30 mass % or less relative to the mixed powder, and

the heat treatment is performed at 350° C. or more and 410° C. or less.