| 简介 |
PROBLEM TO BE SOLVED : To provide a method of producing a rare earth magnet, by which a rare earth magnet excellent in magnetic characteristics can be produced.
SOLUTION : A hydrogenation material containing hydrogen compound of rare earth element and Fe is subjected to the following dehydrogenation treatment. A temperature of the hydrogenation material is raised to a temperature Thigh of 870°C or higher in hydrogen atmosphere, and on and after reaching the temperature Thigh, depressurization of atmosphere is started. The depressurization is performed until hydrogen pressure in the atmosphere comes to be a predetermined value P1 which is 101 hPa or less. While depressurizing the hydrogen pressure from the predetermined value P1 down to a predetermined value P2 of 10.1 Pa or less, the temperature is lowered at a predetermined temperature drop rate down to a temperature Tlow which is 700°C to less than 850°C. The hydrogenation material is held at the temperature Tlow in a depressurized atmosphere in which the hydrogen pressure is the predetermined value P2 or less. Assuming that Vp is exhaust speed of hydrogen, VH is saturation storage amount of hydrogen, and α is a constant of 0.97-3.0, temperature drop speed ΔT/Δt satisfies ΔT/Δt=αlog10(Vp/(100×VH)). During a period from depressuring start Sp to end of temperature holding, the hydrogenation material is applied with a strong magnetic field pf 4T or higher.
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