公开(公告)号：US11742120B2

公开(公告)日：2023-08-29

申请号：US17520452

申请日：2021-11-05

Applicant: BEIJING UNIVERSITY OF TECHNOLOGY

Inventor： Weiqiang Liu ,  Hao Chen ,  Ming Yue ,  Zhi Li ,  Yantao Yin ,  Yuqing Li ,  Hongguo Zhang

IPC: H01F1/057 ,  H01F1/053 ,  H01F1/055 ,  H01F7/02 ,  H01F41/02 ,  B22F9/04 ,  B22F9/02

CPC classification number: H01F1/0573 ,  B22F9/023 ,  B22F9/04 ,  H01F1/0536 ,  H01F1/0551 ,  H01F1/0553 ,  H01F1/0557 ,  H01F1/0577 ,  H01F7/021 ,  H01F41/0266 ,  H01F41/0273 ,  H01F41/0293

Abstract: A two-step diffusion method for preparing high-performance dual-main-phase sintered mischmetal-iron-boron magnet belongs to the preparing technical field of rare earth permanent magnet materials. The compositions of the two main phase alloys are RE-Fe—B (RE is Nd or Pr) and (Nd, MM)-Fe—B (MM is mischmetal), respectively. First, PrHoFe strip-casting alloy is used as a diffusion source. Next, a PrHo-rich layer is uniformly coated on the surface of (Nd, MM)-Fe—B hydrogen decrepitation powders. The higher anisotropic fields of Pr2Fe14B and Ho2Fe14B are used to improve the coercivity. Then, the ZrCu strip-casting alloy is used as a diffusion source. A Zr-rich layer is uniformly coated on the surface of the powders after the first-step diffusion, which prevents the growth of the MM-rich main phase grains during the sintering process and the inter-diffusion between the two main phases, thus obtaining high coercivity.

公开(公告)号：US20220059262A1

公开(公告)日：2022-02-24

申请号：US17520452

申请日：2021-11-05

Applicant: BEIJING UNIVERSITY OF TECHNOLOGY

Inventor： Weiqiang Liu ,  Hao Chen ,  Ming Yue ,  Zhi Li ,  Yantao Yin ,  Yuqing Li ,  Hongguo Zhang

IPC: H01F1/055 ,  H01F7/02 ,  H01F1/053

Abstract: A two-step diffusion method for preparing high-performance dual-main-phase sintered mischmetal-iron-boron magnet belongs to the preparing technical field of rare earth permanent magnet materials. The compositions of the two main phase alloys are RE-Fe—B (RE is Nd or Pr) and (Nd, MM)-Fe—B (MM is mischmetal), respectively. First, PrHoFe strip-casting alloy is used as a diffusion source. Next, a PrHo-rich layer is uniformly coated on the surface of (Nd, MM)-Fe—B hydrogen decrepitation powders. The higher anisotropic fields of Pr2Fe14B and Ho2Fe14B are used to improve the coercivity. Then, the ZrCu strip-casting alloy is used as a diffusion source. A Zr-rich layer is uniformly coated on the surface of the powders after the first-step diffusion, which prevents the growth of the MM-rich main phase grains during the sintering process and the inter-diffusion between the two main phases, thus obtains high coercivity.