Rare earth-cobalt system permanent magnetic alloys and method of

Abstract

Permanent magnetic alloys comprising 11.5-12.5% rare earth components of which 6.3-12% is samarium and 0.5-6.2% is yttrium; 0.2-2.5% hafnium, 19.5-26.5% iron, 7-10.5% copper, and 52-70.7% cobalt, the ranges of the components being in atomic ratios. The alloys are prepared by obtaining 1-50 .mu.m. powders of the components, compacting the powder after magnetic field orientation sintering the compacted powders at 1160.degree.-1220.degree. for 1-10 hours, cooling the sintered body at a rate of at least 1.degree. C./second until the temperature is about 900.degree. C., and then annealing the body at 750.degree.-900.degree. C.