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AssigneeShin-Etsu Chemical Co., Ltd.
InventorsYoshio Yamanaka, Kazuyoshi Watanabe, Masakatsu Honshima, Hideaki Kikuchi
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Permanent magnets are disclosed having a very high coercive force and a very great maximum energy product, and consisting essentially of a rare earth-cobalt based alloy. The alloy is expressed by the formula Sm.sub.1.sub.-u Ce.sub.u (Co.sub.1.sub.-v.sub.-w.sub.-x Cu.sub.v Fe.sub.w Mn.sub.x).sub.z where 0.ltoreq.u.ltoreq.0.20, 0.08.ltoreq.v.ltoreq.0.20, 0.ltoreq.w.ltoreq.0.08, 0.01.ltoreq.x.ltoreq.0.15 and 6.0.ltoreq.z.ltoreq.7.8, preferably 7.2.ltoreq.z.ltoreq.7.8. By using these alloys, the magnetic properties of the resultant permanent magnets are superiorly affected, and the magnet-preparing process is rendered much simplified. This is also because the conventional heat aging step may be eliminated, particularly when the z value is within the preferred range.
A process for the preparation of a permanent magnet which comprises the steps of shaping the powder of an alloy expressed by the formula Sm.sub.1.sub.-u Ce.sub.u (Co.sub.1.sub.-v.sub.-w.sub.-x Cu.sub.v Fe.sub.w Mn.sub.x).sub.z where 0.ltoreq.u.ltoreq.0.20, 0.08.ltoreq.v.ltoreq.0.20, 0.ltoreq.w.ltoreq.0.08, 0.01.ltoreq.x.ltoreq.0.15, and 7.2.ltoreq.z.ltoreq.7.8, into a block by compression molding in a magnetic field, subjecting said block to sintering at a temperature in the range of from 1,170.degree. to 1,270.degree. C, and cooling the thus sintered block at a cooling velocity between 1.degree. C/second and 30.degree. C/second to a temperature of about 800.degree. C, with subsequent cooling to room temperature without any intermediate aging step.
A process for the preparation of a permanent magnet which comprises the steps of shaping the powder of an alloy expressed by the formula Sm.sub.1.sub.-u Ce.sub.u (Co.sub.1.sub.-v.sub.-w.sub.-x Cu.sub.v Fe.sub.w Mn.sub.x).sub.z where 0.ltoreq.u.ltoreq.0.20, 0.08.ltoreq.v.ltoreq.0.20, 0.ltoreq.w.ltoreq.0.08, 0.01.ltoreq.x.ltoreq.0.15, and 7.2.ltoreq.z.ltoreq.7.8, into a block by compression molding in a magnetic field, subjecting said block to sintering at a temperature in the range of from 1,170.degree. to 1,270.degree. C, and cooling the thus sintered block at a cooling velocity between 1.degree. C/second and 30.degree. C/second to a temperature of about 800.degree. C, aging the thus cooled block at this temperature and thereafter cooling the aged block to room temperature.
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