| 简介 |
PROBLEM TO BE SOLVED : To provide a method of manufacturing a rare earth alloy powder for permanent magnet, capable of stably obtaining high coercive force without reducing residual magnetization on the basis of, e.g. the analysis of the influence of reaction velocities in HDDR treatment while obviating the necessity of the use of large amounts of expensive heavy rare earth elements for a composition. SOLUTION : A change in the hydrogen releasing velocity at dehydrogenation in HDDR treatment becomes a change in the recombination reaction velocity and consequently has a major influence on the magnetic properties of a magnetic powder. Based on the above, respective reaction velocities of dehydrogenation/ recombination reaction are changed in stages by the control of atmosphere, e.g. pressure control, and the treatment is allowed to proceed at high hydrogen releasing reaction velocity until 0.2 wt.% (2, 000 ppm) to 0.050 wt.% (500 ppm) hydrogen content in raw material powder is reached and at low reaction velocity until <=0.010 wt.% (100 ppm) is reached. By this method, the rare earth alloy powder for permanent magnet, having high coercive force, can be manufactured without decreasing residual magnetization while obviating the necessity of incorporation of large amounts of rare earth elements into the composition. |
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