Rare earth-transition metal-based magnet powder and its manufacturing method

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PROBLEM TO BE SOLVED : To provide rare-earth/transition-metal/nitrogen-based magnet powder in which the degree of agglomeration is lowered and magnetic properties are improved by regulating the particle size distribution of the magnetic powder to a specific pattern and to provide a method for efficiently manufacturing the magnet powder by carrying out grinding by using specific equipment/conditions. SOLUTION : The rare-earth/transition-metal/nitrogen-based magnet powder has a particle size distribution of 1 to 5 μm average particle size (D50) and ≤5μm particle size (D50-D70) width and also has ≤4 degree of agglomeration (X). The coarse powder of rare-earth/transition-metal/nitrogen-based magnet having >5 μm average particle size is introduced into a grinding machine which is either of a medium-stirring mill and a bead mill, and rotated together with a grinding medium, such as metal balls or ceramic balls, in the grinding machine. Balls of 0.1 to 1 mm ball diameter are used as the grinding medium and the rotational circumferential speed of the grinding machine is made to 10 to 20 m/s to pulverize the coarse powder of the rare-earth/transition-metal/nitrogen-based magnet. By this method, the rare-earth/transition-metal/nitrogen-based magnet powder can be manufactured. COPYRIGHT : (C)2004, JPO