公开(公告)号：US20220293310A1

公开(公告)日：2022-09-15

申请号：US17695011

申请日：2022-03-15

Applicant: TDK CORPORATION

Inventor： Ikuya KOKAWA ,  Yoshinori FUJIKAWA ,  Kenichi SUZUKI ,  Yasushi ENOKIDO

IPC: H01F1/055 ,  H01F41/02 ,  H01F7/02

Abstract: The rare-earth-based magnet powder has an average value of 0.65 or more as sphericity P1 defined by an equation (1) of P1=Ls/Ll. In the equation (1), Ll is a length or a long side of a rectangle that circumscribes the rare-earth-based magnet powder in a photomicrograph so that an area of the rectangle is minimized, and Ls is a length of a short side of the rectangle that circumscribes the rare-earth-based magnet powder in the photomicrograph so that the area of the rectangle is minimized.

公开(公告)号：US20240331899A1

公开(公告)日：2024-10-03

申请号：US18607699

申请日：2024-03-18

Applicant: TDK CORPORATION

Inventor： Ikuya KOKAWA ,  Yoshinori Fujikawa ,  Takahiro Suwa ,  Wakako Okawa

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

CPC classification number: H01F1/0577 ,  B22F3/16 ,  B22F3/24 ,  B22F9/023 ,  B22F9/04 ,  C22C38/002 ,  C22C38/005 ,  C22C38/06 ,  C22C38/10 ,  C22C38/14 ,  C22C38/16 ,  B22F2003/248 ,  B22F2009/044 ,  B22F2201/02 ,  B22F2201/20 ,  B22F2202/05 ,  B22F2301/355 ,  B22F2998/10 ,  B22F2999/00

Abstract: An R-T-B based permanent magnet comprises main phases each comprising a core and a shell, and a grain boundary phase adjacent to the main phases. The shell comprises Tb. The shell has a thickness of 70 nm or more. The shell has a Tb concentration with a maximum of 1.7 at % or more.