公开(公告)号：US10784028B2

公开(公告)日：2020-09-22

申请号：US15440443

申请日：2017-02-23

Applicant: TDK CORPORATION

Inventor： Tamotsu Ishiyama ,  Masashi Miwa ,  Takashi Watanabe

IPC: H01F41/02 ,  H01F1/057 ,  B22F3/10 ,  B22F3/24 ,  H01F1/053 ,  B22F3/16 ,  B22F5/00 ,  B22F9/04 ,  C21D3/06 ,  C22C38/00 ,  C22C38/06 ,  C22C38/10 ,  C22C38/14 ,  C22C38/16 ,  B22F1/00 ,  H01F1/058

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. An average grain size of the main phase grains is 0.8 μm to 2.8 μm. The R-T-B based permanent magnet contains at least C and Ga in addition to R, T, and B. B is contained at 0.71 mass % to 0.86 mass %. C is contained at 0.13 mass % to 0.34 mass %. Ga is contained at 0.40 mass % to 1.80 mass %. A formula (1) of 0.14≤[C]/([B]+[C])≤0.30 is satisfied, where [B] is a B content represented by atom %, and [C] is a C content represented by atom %.

公开(公告)号：US11335484B2

公开(公告)日：2022-05-17

申请号：US16965905

申请日：2019-01-29

Applicant: TDK CORPORATION

Inventor： Masaki Tomita ,  Ryuji Hashimoto ,  Takashi Watanabe

IPC: H01F1/059

Abstract: A permanent magnet including R and T. R are rare earth elements including Sm and at least one selected from Y and Gd. T is Fe alone or Fe and Co. T maybe partly substituted with M, and M is one or more selected from Ti, V, Cr, Mo, W, Zr, Hf, Nb, Ta, Al, Si, Cu, Zn, Ga and Ge. In a total content of R, Sm content is 60 at % or more and 95 at % or less, and a total content of Y and Gd is 5 at % or more and 35 at % or less. The permanent magnet includes main phase crystal grains having a ThMn12 type crystal structure.