公开(公告)号：US11636962B2

公开(公告)日：2023-04-25

申请号：US17202410

申请日：2021-03-16

Applicant: TDK Corporation

Inventor： Masashi Miwa ,  Koji Miura ,  Taeko Tsubokura

IPC: H01F1/057 ,  B22F3/16 ,  B22F9/04 ,  C22C38/00 ,  C22C28/00 ,  C22C33/02 ,  C22C38/06 ,  C22C38/10 ,  C22C38/16 ,  C22C38/14 ,  H01F41/02

Abstract: Provided is a permanent magnet including a rare-earth element R, a transition metal element T, B, Zr, and Cu. The permanent magnet contains main phase grains including Nd, T, and B, and grain boundary multiple junctions, the grain boundary multiple junction is a grain boundary surrounded by three or more of the main phase grains, one of the grain boundary multiple junctions contains a ZrB2 crystal and an R—Cu-rich phase, a concentration of B in the grain boundary multiple junction containing both the ZrB2 crystal and the R—Cu-rich phase is from 5 to 20 atomic %, a concentration of Cu in the grain boundary multiple junction containing both the ZrB2 crystal and the R—Cu-rich phase is from 5 to 25 atomic %, and a surface layer part of the main phase grain includes at least one kind of heavy rare-earth element among Tb and Dy.

公开(公告)号：US10748686B2

公开(公告)日：2020-08-18

申请号：US15939778

申请日：2018-03-29

Applicant: TDK CORPORATION

Inventor： Yoshinori Fujikawa ,  Masashi Miwa

IPC: H01F41/02 ,  H01F1/057 ,  C22C38/00

Abstract: An R-T-B based sintered magnet including a plural number of main phase particles having an R2T14B type crystal structure. R is at least one rare earth element essentially including heavy rare earth elements RH, T is at least one transition metal element essentially including Fe or Fe and Co, and B is boron. At least one of the main phase particles is a reverse core-shell main phase particle including a core part and a shell part, in which CRC/CRS>1.0 is satisfied when a total RH concentration (at %) in the core part is defined as CRC and a total RH concentration (at %) in the shell part is defined as CRS. An existence ratio of the reverse core-shell main phase particles is larger in a surface layer part of the magnet than in a central part of the magnet.

公开(公告)号：US10672546B2

公开(公告)日：2020-06-02

申请号：US15440660

申请日：2017-02-23

Applicant: TDK CORPORATION

Inventor： Masashi Miwa ,  Takurou Iwasa ,  Tamotsu Ishiyama

IPC: H01F1/057 ,  B22F9/04 ,  B22F3/16 ,  B22F3/24 ,  C22C33/02 ,  C22C33/04 ,  C22C38/00 ,  C22C38/06 ,  C22C38/10 ,  C22C38/14

Abstract: An R-T-B based permanent magnet includes main phase grains composed of R2T14B type compound. R is a rare earth element. T is iron group element(s) essentially including Fe or Fe and Co. B is boron. The magnet contains at least C, Ga, and M selected from Zr, Ti, and Nb in addition to R, T, and B. B is contained at 0.71 mass % to 0.88 mass %. C is contained at 0.15 mass % to 0.34 mass %. Ga is contained at 0.40 mass % to 1.40 mass %. M is contained at 0.25 mass % to 2.50 mass %. A formula (1) of 0.14≤[C]/([B]+[C])≤0.30 and a formula (2) of 5.0≤[B]+[C]−[M]≤5.6 are satisfied, where [B], [C], and [M] are respectively a content of B, C, and M by atom %.

公开(公告)号：US10529473B2

公开(公告)日：2020-01-07

申请号：US15440667

申请日：2017-02-23

Applicant: TDK CORPORATION

Inventor： Takurou Iwasa ,  Masashi Miwa

IPC: H01F1/053 ,  B22F9/04 ,  B22F3/12 ,  B22F5/00 ,  C21D3/06 ,  C22C38/00 ,  C22C38/06 ,  C22C38/10 ,  C22C38/14 ,  C22C38/16 ,  H01F1/06

Abstract: An R-T-B based permanent magnet includes R-T-B based compounds as main-phase crystal grains. R is a rare earth element. T is iron group element(s) essentially including Fe or Fe and Co. B is boron. A two-grain boundary is contained between the two adjacent main-phase crystal grains. An average grain size of the main-phase crystal grains is 0.9 μm or more and 2.8 μm or less. A thickness of the two-grain boundary is 5 nm or more and 200 nm or less.

公开(公告)号：US09997284B2

公开(公告)日：2018-06-12

申请号：US14409186

申请日：2013-06-21

Applicant: TDK Corporation

Inventor： Masashi Miwa ,  Atsushi Fujiwara ,  Eiji Kato ,  Taeko Tsubokura ,  Koji Mitake ,  Chikara Ishizaka

IPC: H01F1/057 ,  C22C38/00 ,  C22C38/06 ,  C22C38/10 ,  C22C38/14 ,  C22C38/16 ,  B22F3/10 ,  H01F7/02

CPC classification number: H01F1/0577 ,  B22F3/10 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/06 ,  C22C38/10 ,  C22C38/14 ,  C22C38/16 ,  H01F7/02

Abstract: A sintered magnet of a preferred embodiment has a composition comprising: R (R is a rare earth element that must contain any one of Nd and Pr.): 29.5 to 33.0 mass %; B: 0.7 to 0.95 mass %; Al: 0.03 to 0.6 mass %; Cu: 0.01 to 1.5 mass %; Co: 3.0 mass % or less (provided that 0 mass % is not included.); Ga: 0.1 to 1.0 mass %; C: 0.05 to 0.3 mass %; O: 0.03 to 0.4 mass %; and Fe and other elements: a balance, and wherein a content of heavy rare earth elements in total is 1.0 mass % or less, and wherein the following relations are satisfied: 0.29

公开(公告)号：US20150235750A1

公开(公告)日：2015-08-20

申请号：US14378428

申请日：2013-02-13

Applicant: TDK CORPORATION

Inventor： Masashi Miwa ,  Haruna Nakajima ,  Ken-ichi Nishikawa ,  Tetsuya Hidaka ,  Jun Hagiwara ,  Chikara Ishizaka

IPC: H01F7/02

CPC classification number: H01F7/021 ,  B22F1/0007 ,  B22F3/02 ,  B22F3/24 ,  B22F2003/248 ,  B22F2202/05 ,  B22F2999/00 ,  C22C33/0278 ,  C22C38/002 ,  C22C38/005 ,  C22C38/06 ,  C22C38/10 ,  C22C38/14 ,  C22C38/16 ,  H01F1/0577

Abstract: The present invention provides an R-T-B based sintered magnet including R2T14B crystal grains wherein; a grain boundary is formed by two or more adjacent R2T14B crystal grains, an R—O—C concentrated part, in which concentrations of R, O and C are higher than those in the R2T14B crystal grains respectively, is in the grain boundary, and a ratio (O/R) of O atom to R atom in the R—O—C concentrated part satisfies the following formula (1): 0.4

Abstract translation: 本发明提供一种包含R2T14B晶粒的R-T-B系烧结磁体，其中： 晶界由两个或更多个相邻的R2T14B晶粒形成，其中R，O和C的浓度分别高于R2T14B晶粒中的R-O-C浓缩部分在晶界中，并且 R-O-C浓缩部分中的O原子与R原子的比率（O / R）满足下式（1）：0.4 <（O / R）<0.7。