Patent ID: 7507302

Claim:
A nanocomposite magnet powder of an iron-based rare-earth alloy having a composition represented by the general formula: (Fe 1-m T m ) 100-x-y-z-n Q x R y Ti z M n (where T is 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 element selected from the group consisting of the rare-earth metal elements and yttrium; and M is at least one element selected from the group consisting of Nb, Zr, Mo, Ta and Hf), the mole fractions x, y, z, m and n satisfying the inequalities of: 10 at %<x≦25 at %; 6 at %≦y<10 at %; 0.1 at %≦z≦12 at %; 0≦m≦0.5; and 0 at %≦n≦10 at %, respectively, wherein the nanocomposite magnet powder is obtained by an atomization process and includes at least two types of ferromagnetic crystalline phases, in which an R 2 Fe 14 B type compound phase serving as a hard magnetic phase has an average grain size of 10 nm to 200 nm and a soft magnetic phase has an average grain size of 1 nm to 50 nm; a ferromagnetic iron-based boride phase and an α-Fe phase serving as the soft magnetic phase are present on a grain boundary or sub-boundary of the R 2 Fe 14 B type compound phase; and the average crystal grain size of the ferromagnetic iron-based boride phase and α-Fe is smaller than that of the R 2 Fe 14 B type compound phase.