METHOD FOR PRODUCING RARE EARTH ANISOTROPIC MAGNET POWDER

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PROBLEM TO BE SOLVED : To provide a magnet powder with a relatively low Co composition having high saturation magnetic flux density, high coercive force and satisfactory squareness without adopting complicated processes such as Dy diffusion treatment. SOLUTION : The method comprises : a stage A where the fine powder of an (Nd, Pr)-Dy-Fe-Co-B based raw material alloy is prepared; a stage B where the fine powder is heated to occlude hydrogen in the fine powder in the temperature range of <500°C under the hydrogen pressure of 100 to 300 kPa, so as to introduce cracks into the grains, and further, temperature is raised in the temperature range of ≥500°C in a vacuum or an inert gas atmosphere, and thereafter, hydrogen is introduced therein at 750 to <1, 000°C; a stage C where heat treatment is performed at 800 to <900°C under the hydrogen pressure of 100 to 300 kPa for 3 to <8 hr; a stage D where heat treatment is performed at 800 to <900°C under the hydrogen partial pressure of ≤10 kPa for 30 min to <8 hr; and a stage E where cooling is performed. COPYRIGHT : (C)2008, JPO&INPIT