Abstract: A thermally stable permanent magnet with reduced irreversible loss of flux and improved intrinsic coercivity iHc of 15 KOe or more having the following compositon:(Nd.sub.1-.alpha. Dy.sub..alpha.)(Fe.sub.1-x-y-z Co.sub.x B.sub.y M.sub.z).sub.awherein M represents at least one element selected from the group consisting of Nb, Mo, Al, Si, P, Zr, Cu, V, W, Ti, Ni, Cr, Hf, Mn, Bi, Sn, Sb and Ge, 0.01.ltoreq.x .ltoreq.0.4, 0.04.ltoreq.y.ltoreq.0.20, 0.ltoreq.z.ltoreq.0.03, 4.ltoreq.a.ltoreq.7.5 and 0.03.ltoreq..alpha..ltoreq.0.40. This can be manufactured by (a) sintering an alloy having the above composition by a powder metallurgy method, (b) heating the sintered body at 750.degree.-1000.degree. C. for 0.2-5 hours, (c) slowing cooling it at a cooling rate of 0.3.degree.-5.degree. C./min to temperatures between room temperature and 600.degree. C., (d) heating it at 540.degree.-640.degree. C. for 0.2-3 hours, and (e) rapidly cooling it at a cooling rate of 20.degree.-400.degree. C./min.

Abstract: A thermally stable permanent magnet with reduced irreversible loss of flux and improved intrinsic coercivity iHc of 15KOe or more having the following composition:(Nd.sub.1-.alpha. Dy.sub..alpha.)(Fe.sub.1-x-y-z Co.sub.x B.sub.y M.sub.z).sub.awherein M represents at least one element selected from the group consisting of Nb, Mo, Al, Si, P, Zr, Cu, V, W, Ti, Ni, Cr, Hf, Mn, Bi, Sn, Sb and Ge, 0.01.ltoreq.x.ltoreq.0.4, 0.04.ltoreq.y.ltoreq.0.20, 0.ltoreq.z.ltoreq.0.03, 4.ltoreq.a.ltoreq.7.5 and 0.03.ltoreq..alpha..ltoreq.0.40. This can be manufactured by (a) sintering an alloy having the above composition by a powder metallurgy method, (b) heating the sintered body at 750.degree.-1000.degree. C. for 0.2-5 hours, (c) slowly cooling it at a cooling rate of 0.3.degree.-5.degree. C./min to temperatures between room temperature and 600.degree. C., (d) heating it at 540.degree.-640.degree. C. for 0.2-3 hours, and (e) rapidly cooling it at a cooling rate of 20.degree.-400.degree. C./min.

Abstract: A permanent magnet alloy made by adding one or more of Si, Ti, Zr, V, Nb, Cr, and Mo to a known permanent magnet alloy containing rare earth metals, Co, Fe, and Cu. By adding such additives, the amount of substitution of copper required for full precipitation hardening is reduced in the alloy of the present invention for the improvement in magnetic characteristics and thermal stability.

Abstract: A permanent magnet alloy consisting of the composition expressed by a formula-R(CO.sub.1-x-y-z Fe.sub.x Cu.sub.y Hf.sub.z).sub.Awhere R=Sm, Ce or a rare earth element or a combination thereof,0.01.ltoreq.x.ltoreq.0.400.02.ltoreq.y.ltoreq.0.250.001.ltoreq.z.ltoreq.0.15, and6.5.ltoreq.A.ltoreq.8.3.