Patent ID: 7842140

Claim:
An iron-based rare-earth nanocomposite magnet having a composition represented by the formula:T 100−x−y−z−n Q x R y Ti z M n , where T is either Fe alone or Fe in combination with at least one element selected from the group consisting of Co and Ni; Q is at least one element selected from the group consisting of B and C; R is at least one rare-earth element including substantially no La or Ce; and M is at least one metal element selected from the group consisting of Al, Si, V, Cr, Mn, Cu, Zn, Ga, Zr, Nb, Mo, Ag, Hf, Ta, W, Pt, Au and Pb, the mole fractions x, y, z and n satisfying the inequalities of 5 at % ≦x ≦8 at %, 7 at % ≦y ≦10 at %, 0.1 at % ≦z ≦5 at % and 0 at % ≦n ≦10 at %, respectively, wherein the magnet includes R 2 T 14 Q compound phases and α —Fe phases that form a magnetically coupled nanocomposite magnet structure, and wherein the R 2 T 14 Q compound phases have an average crystal grain size of 20 nm or more and the α —Fe phases are present at grain boundary triple points in a grain boundary region between the R 2 T 14 Q compound phases, the grain boundary region having a thickness of 20 nm or less, wherein a ratio of the average crystal grain size of the R 2 T 14 Q compound phases relative to that of the α —Fe phases is 2.0 or more, and wherein the magnet has magnetic properties including a coercivity of at least 400 kA/m and a remanence of at least 0.9 T.