MANUFACTURING METHOD FOR R-T-N MAGNET POWDER

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PROBLEM TO BE SOLVED : To provide an anisotropic rare-earth bonded magnet having a high performance by magnet raw-material powder having a small quantity of impurities and having no pulverization strain. SOLUTION : R-T alloy powder containing no nitrogen is pulverized previously to 5 μm or less, and the impalpable powder is press-molded at a molding pressure of 1 ton/cm2 or less. A molded form is treated thermally for 1 to 3 hr at 550 to 850°C in an inert-gas atmosphere at a pressure of 1 atmospheric pressure or more, and the strain introduced by a mechanical pulverization is removed. A furnace temperature is set at 350 to 600°C, a furnace atmosphere is held for a fixed time in a nitrogen gas containing hydrogen of 50 vol. % or less or a nitrogen-gas atmosphere containing an ammonia gas of 60 vol. % or less after a heat treatment, and a nitriding treatment is conducted.