Two-step diffusion method for preparing high-performance dual-main-phase sintered mischmetal-iron-boron magnet
US11742120B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 5, 2021 |
| Grant date | Aug 29, 2023 |
| Priority date | — |
| Expiry date | Feb 24, 2042 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01F41/0293
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.