For an anisotropic permanent magnet of rare earth alloy powder manufacturing method

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PROBLEM TO BE SOLVED : To efficiently and stably produce anisotropic rare earth alloy powder for a permanent magnet sufficiently high in magnetic anisotropy and having high coercive force by coarsely crushing an alloy ingot having a specified compsn., thereafter executing temp. raising and holding under heating under specified conditions in the evacuated air current of an inert gas and pulverizing the powder obtd. by executing cooling. SOLUTION : An alloy ingot is composed of, by atom, 11 to 15% rare earth elements, 76 to 84% Fe or Fe in which a part is substituted with Co, 0.05 to 5% of one or more kinds among eight kinds of Ga or the like, 0.01 to 0.3% Cu and 5 to 9% B, which is coarsely crushed to form into powder composed of an Nd2 Fe14 B type compound. The temp. of this powder is raised in gaseous H2 , it is held under heating at 750 to 900 deg.C for 15 min to 8 hr to form its structure into the mixed one of four phases. Furthermore, it is subjected to dehydrogenation treatment of executing holding at 700 to 900 deg.C for 5 min to 8 hr in an evacuated air current by an inert gas of Ar or the like. Next, the powder with 0.05 to 1 μm average grain size obtd. by executing cooling is pulverized to regulate its average grain size to 20 to 400 μm.