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

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PROBLEM TO BE SOLVED : To provide a manufacturing method of magnetic powder for forming a sintered compact of a rare earth magnet precursor in which the magnetic power without a coarse particle in a composition is exquisitely and efficiently screened to allow manufacturing the magnetic powder including the composition consisting of optimum nano-sized crystal grains. SOLUTION : There is provided a manufacturing method of a magnetic powder p for forming a sintered compact S which comprises crystal grains which are a Nd-Fe-B based main phase of a nanocrystal composition and a grain boundary phase, and is a precursor of a rare earth magnet which is formed by applying hot plastic processing to the sintered compact S to add anisotropy and diffusing an alloy in it for improving coercive field strength. In the manufacturing method, a molten metal is discharged on a cooling roller R to produce a quenched ribbon B, and the quenched ribbon is smashed into a size range between 50 μm and 1000 μm to produce the magnetic powder within a mass range between 0.0003 mg and 0.3 mg. The magnetic powder within the mass range is checked whether the magnetic powder is attracted to a magnet whose surface magnetic flux density is 2 mT or less. The magnetic powder p that is not attracted, is selected to be the magnetic powder to form the sintered compact S. COPYRIGHT : (C)2013, JPO&INPIT