RARE EARTH-IRON-MANGANESE-NITROGEN BASED MAGNET POWDER AND ITS PRODUCTION METHOD

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PROBLEM TO BE SOLVED : To provide a method for producing rare earth-iron-manganese-nitrogen based magnet powder exhibiting excellent oxidation resistance and high magnetic characteristics, especially high rectangularity in demagnetization curve, and having high remanent magnetic flux density, and to provide rare earth-iron-manganese-nitrogen based magnet powder produced by that method. SOLUTION : Mother alloy powder produced from rare earth oxide powder and transition metal powder containing iron and manganese as essential components by reducing diffusion is classified before nitriding to obtain mother alloy powder having a grain size of 20-76 μm and an accumulated volume percentage D50 (means particle size) of 30-35 μm. Furthermore, rare earth-iron-manganese-nitrogen based magnet powder obtained after nitriding is classified and fine powder is removed such that the content of magnetic powder having a particle size smaller than 20 μm becomes 18 wt% or less. COPYRIGHT : (C)2006, JPO&NCIPI