MANUFACTURING METHOD FOR MAGNETIC POWDER FOR FORMING SINTERED BODY OF RARE-EARTH MAGNET PRECURSOR

摘要

A method for producing magnetic powder for forming a sintered body that is a precursor of a rare-earth magnet. Provided is a method for producing magnetic powder for forming a sintered body that is a precursor of a rare-earth magnet, which can produce magnetic powder with a structure containing optimal nanosized crystal grains by accurately and efficiently sorting out magnetic powder containing no coarse grains in the structure thereof. A method for producing magnetic powder p for forming a sintered body S that is a precursor of a rare-earth magnet, the sintered body S including an Nd-Fe-B-based main phase with a nanocrystalline structure, and a grain boundary phase around the main phase, and the rare-earth magnet being adapted to be formed by applying hot deformation processing to the sintered body S for imparting anisotropy thereto and diffusing an alloy for improving coercivity therein, the method including discharging a metal melt onto a chill roll R to produce a quenched ribbon B, and grinding the quenched ribbon B into grains in the size range of 50 to 1000 µm to produce magnetic powder in the mass range of 0.0003 to 0.3 mg; conducting a test to see whether or not the magnetic powder in the mass range adsorbs onto a magnet with a surface magnetic flux density of 2 mT or less, and sorting out magnetic powder p that has not adsorbed onto the magnet, as the magnetic powder for forming the sintered body S.