Alloy for use in preparation of R-T-B-based sintered magnet and process for preparing R-T-B-based sintered magnet
US6444048B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 2000 |
| Grant date | Sep 3, 2002 |
| Priority date | — |
| Expiry date | Jun 19, 2020 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB22F2998/10
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Processes for the preparation of a sintered alloy comprising R2Fe14B as a magnetic phase constituting a main phase include a binary alloy process wherein a main phase alloy having a lower R content than the above phase is mixed with a grain boundary phase alloy rich in R component and serving as a liquid phase in the sintering in order to prepare a mixture to be used as the starting material. The conventional main phase alloy has a structure comprising the R2Fe14B phase and, in addition, a large amount of an easily oxidizable lamella R-rich phase and a harmful dendrite &agr; phase. On the other hand, the main phase alloy of the invention has a low dendrite a phase content and a low lamella R-rich phase and contains a lamella &agr; Fe phase. This contributes to excellent oxidation resistance and improved properties of the magnet. The preparation of a sintered magnet by mixing the main phase alloy with the grain boundary phase alloy by the binary alloy method can reduce abnormal growth of crystal grains.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.