Method for preparing R—Fe—B sintered magnet
US10937578B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 20, 2017 |
| Grant date | Mar 2, 2021 |
| Priority date | — |
| Expiry date | Dec 13, 2037 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC22C38/005
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
An R—Fe—B base sintered magnet is prepared through the steps of providing an alloy fine powder having a predetermined composition, compression shaping the alloy fine powder in an applied magnetic field into a compact, sintering the compact at a temperature of 900-1,250° C. into a sintered body, cooling the sintered body to 400° C. or below, high-temperature heat treatment including placing a metal, compound or intermetallic compound containing HR which is Dy, Tb and/or Ho, on the surface of the sintered body, heating at a temperature from more than 950° C. to 1,100° C., for causing grain boundary diffusion of HR into the sintered body, and cooling to 400° C. or below, and low-temperature heat treatment including heating at a temperature of 400-600° C. and cooling to 300° C. or below. The sintered magnet produces a high coercivity despite a low content of Dy, Tb and Ho.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.