Magnetic Properties of SmFe₇N_x+αFe Nanocomposite Magnets and their Application

Abstract

Nanocomposite magnet materials with composition of (Sm₈Zr₃Fe₈₅Co₄)₈₅N₁₅ were prepared by rapidly quenching method including heat treatment and nitrogenation. The ranges of grain sizes are 20-40nm. X-ray diffraction study indicated that hard phase is SmFe₇N_x, and that soft phase are a-Fe. By compositional analysis of fine grains using TEM-EDS, it is revealed that magnetically hard phase of SmFe₇N_x have a composition of Sm richer ratio than that of 1-7 stoichiometry. Magnetic properties of those powders were as follows : Br=0.99T, Hcj=656kA/m, (BH)max=140kJ/m³, Hk/H_cJ=33%. Magnetic properties of their bonded with epoxy resin through die press process were as follows: Br=0.76T, Hcj=672kA/m, (BH)max=96kJ/m³, Hk/H_cJ = 35%. Performance of spindle motors equipped those bonded fabricated in ring shape meets magnetic properties of bonded magnets.