公开(公告)号：US20170250015A1

公开(公告)日：2017-08-31

申请号：US15440660

申请日：2017-02-23

Applicant: TDK CORPORATION

Inventor： Masashi MIWA ,  Takurou IWASA ,  Tamotsu ISHIYAMA

IPC: H01F1/055 ,  C22C38/14 ,  C22C38/10 ,  C22C38/06 ,  C21D6/00 ,  B22D11/00 ,  C22C33/04 ,  B22F9/04 ,  B22F3/16 ,  B22F3/24 ,  C22C38/16 ,  C22C38/00

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：US20170250013A1

公开(公告)日：2017-08-31

申请号：US15440443

申请日：2017-02-23

Applicant: TDK CORPORATION

Inventor： Tamotsu ISHIYAMA ,  Masashi MIWA ,  Takashi WATANABE

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

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 %.