US 11,869,690 B2
Rare earth magnet and producing method thereof
Noritsugu Sakuma, Mishima (JP); Tetsuya Shoji, Susono (JP); Akihito Kinoshita, Mishima (JP); and Akira Kato, Mishima (JP)
Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP)
Filed by TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP)
Filed on Jan. 19, 2022, as Appl. No. 17/578,856.
Claims priority of application No. 2021-042183 (JP), filed on Mar. 16, 2021.
Prior Publication US 2022/0301753 A1, Sep. 22, 2022
Int. Cl. H01F 1/057 (2006.01); H01F 41/02 (2006.01); B22F 3/24 (2006.01); C22C 38/00 (2006.01); C22C 38/10 (2006.01)
CPC H01F 1/0577 (2013.01) [C22C 38/005 (2013.01); C22C 38/10 (2013.01); H01F 41/0293 (2013.01); C22C 2202/02 (2013.01); H01F 41/0266 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A rare earth magnet, comprising:
a main phase having a composition represented by, in molar ratio, R12T14B, where R1 is one or more elements selected from the group consisting of Y and rare earth elements and T is one or more transition elements mandatorily containing one or more elements selected from the group consisting of Fe, Co and Ni, and
a grain boundary phase present around the main phase,
wherein:
the main phase has a core part and a shell part present around the core part,
the molar ratio of R2, where R2 one or more elements selected from the groups consisting of Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, in the shell part is higher than the molar ratio of R2 in the core part,
the rare earth magnet satisfies the following relationships, denoting the abundances of R2 and Ce occupying 4f site of the shell part as R24f and Ce4f, respectively, and denoting the abundances of R2 and Ce occupying 4g site of the shell part as R24g and Ce4g, respectively:
0.44≤R24g/(R24f+R24g)≤0.70, and
0.04≤(Ce4f+Ce4g)/(R24f+R24g), and
the rare earth magnet further has a secondary shell part between the core part and the shell part, wherein the molar ratio of R4, where R4 is one or more elements selected from the group consisting of Pr, Nd, Pm, Sm and Eu, in the secondary shell part is higher than the molar ratio of R4 in the core part.