Patent ID: 7713360

Claim:
A rare earth permanent magnet comprising a magnetic intermetallic compound comprising R, T and an unavoidable impurity, wherein R is one or more rare earth elements, T is three or more transition metal elements and comprises principally Fe, Cu and Co; wherein the magnetic intermetallic compound has an T/R atomic ratio of 6 to 14; a magnetocrystalline anisotropy energy of at least 1 MJ/m 3 ; a Curie point of at least 100° C.; average particle diameter of at least 3 μm; wherein the rare earth permanent magnet has a structure that gives a pinning initial magnetization curve and lacks microstructure of 1 nm or above inside the magnetic intermetallic compound; wherein no less than 25 to 35 atomic % of the transition metal T content is replaced by Cu; and wherein the magnetic intermetallic compound has a TbCu 7 structure, and wherein the intermetallic compound has a composition formula: R′(Co 1-x-y-a Fe x Cu y T′ a ) z Formula (II) wherein R′ is one or more rare earth elements comprising Y and comprises principally Sm or Ce; T′ is one or more transition metal elements selected from the group consisting of Zr, Ti, V, Mo, Nb, W, Hf, Mn, Cr, and Ni; and x, y, a and z are numbers that satisfy 0.05≦x≦0.30, 0.25≦y≦0.35, 0.001≦a≦0.05 and 6≦z≦14.