METHOD FOR PRODUCING RARE EARTH PERMANENT MAGNET

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According to one embodiment of the present invention, a method for manufacturing a rare earth permanent magnet comprises : a preparation step of preparing rare earth-based magnet powder; a sintering step of sintering the rare earth-based magnet powder to manufacture a sintered magnet; a spreading material application step of applying a spreading material including heavy rare earth-based element on a surface of the sintered magnet; a spreading material spread step of spreading the spreading material according to a grain boundary of the sintered magnet; and a multiple heat treatment step of gradually reducing the temperature and performing heat treatment the sintered magnet in which the spreading material is spread along the grain boundary to form a rare earth alloy base and spreading the rare earth alloy base along the grain boundary of the sintered magnet. Therefore, coercive force and heat characteristics of the rare earth permanent magnet can be improved.(AA) Manufacturing rare earth-based magnet powder(BB) Manufacturing a sintered magnet by sintering(CC) Applying a spreading material on a surface of the sintered magnet(DD) Primarily treating with heat at 850-950° C(EE) Primarily cooling under an inert atmosphere(FF) Secondarily treating with heat at 550-650° C(GG) Secondarily cooling under the inert atmosphere(HH) Removing internal stressCOPYRIGHT KIPO 2018