Method of producing neodymium-iron-boron permanent magnet
US4837109A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 10, 1987 |
| Grant date | Jun 6, 1989 |
| Priority date | — |
| Expiry date | Jul 10, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01F1/0573
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method of producing a neodymium-iron-boron permanent magnet alloy having a composition of 25.0-50.0 weight % of neodymium, 0.3-5.0 weight % of boron and balance substantially iron, including the steps of adding metal calcium, calcium hydride or a mixture thereof as a reducing agent to neodymium fluoride, iron and boron (or ferroboron), and further adding thereto at least one of calcium chloride, sodium chloride and potassium chloride as a flux, melting the resulting mixture in an inert gas atmosphere, or in a reducing gas atmosphere or substantially in vacuum at 1,000.degree.-1,300.degree. C., thereby reducing said neodymium fluoride to provide said alloy with as small a calcium content as 0.1 weight % or less. The starting materials may contain dysprosium fluoride and niobium to provide Nd-Dy-Fe-B-Nb alloys containing 0.5-15.0 weight % Dy and 0.05-5.0 weight % Nb. This method makes it possible to produce Nd-Fe-B or Nd-Dy-Fe-B-Nb permanent magnet alloys with as small a calcium content as 0.1 weight % or less directly from starting materials. Accordingly, it is economically advantageous over the conventional reduction method which produces mother alloys.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.