US 12,272,473 B2
Anisotropic rare earth sintered magnet and method for producing the same
Tadao Nomura, Fukui (JP); and Masayuki Kamata, Tsuruga (JP)
Assigned to SHIN-ETSU CHEMICAL CO., LTD., Tokyo (JP)
Filed by SHIN-ETSU CHEMICAL CO., LTD., Tokyo (JP)
Filed on Oct. 28, 2022, as Appl. No. 18/050,748.
Claims priority of application No. 2021-181252 (JP), filed on Nov. 5, 2021; and application No. 2022-141632 (JP), filed on Sep. 6, 2022.
Prior Publication US 2023/0148121 A1, May 11, 2023
Int. Cl. H01F 1/057 (2006.01); B22F 3/24 (2006.01); H01F 41/02 (2006.01)
CPC H01F 1/0577 (2013.01) 18 Claims
OG exemplary drawing
 
1. An anisotropic rare earth sintered magnet having a composition of a formula Rx(Fe1−aCoa)100−x−y−zByMz, in which the main phase is formed of an R2Fe14B compound crystal, the main phase grains existing therein are such that the Ce/R′ ratio in the center part of the grains is lower than the Ce/R′ ratio in the outer shell part thereof, and a Ce-containing R′-rich phase and a Ce-containing R′(Fe,Co)2 phase exist in the grain boundary part, wherein a boundary phase containing 20 at % or more R and having a thickness of 0.1 nm or more and 20 nm or less is formed between the main phase and the R′(Fe,Co)2 phase,
R is two or more kinds of elements selected from rare earth elements and indispensably including Nd and Ce, M is one or more kinds of elements selected from the group consisting of Al, Si, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb, and Bi, and x, y, z, and a each satisfy 12≤x≤17 at %, 3.5≤y≤6.0 at %, 0≤z≤3 at %, and 0≤a≤0.1,
R′ is one or more kinds of elements selected from rare earth elements and indispensably including Nd,
a content of Ce in the R′ rich phase is 4.1 at % or more and 16.3 at % or less, and
a content of CE in the R′(Fe, Co), phase is 12.8 at % or more and 20.8 at % or less.