The rare earth-based magnet iron-base and its manufacturing method

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An iron-based rare-earth nanocomposite magnet according to the present invention includes an Nd 2 Fe 14 B phase and an ±-Fe phase and has a composition represented by the compositional formula : T 100-x-y-z-n (B 1-q C q ) x R y Ti z M n , where T is at least one transition metal element selected from the group consisting of Fe, Co and Ni and always including Fe, 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, and the mole fractions x, y, z, n and q satisfy the inequalities of : 4 at%‰¦x‰¦10 at%, 6 at%‰¦y‰¦10 at%, 0.05 at%‰¦z‰¦5 at%, 0 at%‰¦n‰¦10 at%, and 0.05‰¦q‰¦0.5, respectively. The magnet includes 5 vol% to 60 vol% of ±-Fe phase with an average crystal grain size of 1 nm to 50 nm and 40 vol% to 90 vol% of Nd 2 Fe 14 B phase with an average crystal grain size of 5 nm to 100 nm. A non-magnetic phase including at least Ti and C (carbon) is present on the grain boundary between the ±-Fe and Nd 2 Fe 14 B phases.