TbCu_7型構造Sm-Fe-Co-Mn系窒化化合物磁石の磁気特性(ハード磁性材料)

概要

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An experiment was carried out to examine the effect of composition, heat treatment, and nitrogenation conditions on the magnetic properties of Sm-Fe-Co-Mn nitrides with TbCu_7-type structure. The optimum preparation conditions of the compounds were as follows: composition {Sm_<10>(Fe_<0.9>Co_<0.1>)_<89.5>Mn_<0.5>}_<84>N_<16>; roller velocity 50 m/s; heat treatment 700℃×60 min in high-purity Ar gas; and nitrogenation condition 420℃×15 h in high-purity N_2 gas. Typical magnetic properties of the obtained powders were as follows: J_r=0.96T, H_<cJ>=699.2kA/m, (BH)_<max>=138.3kJ/m^3 (17.4 MGOe), and T_c=508℃. Recoil loops of the hysteresis curve and X-ray analysis showed that the sample was an exchange spring magnet. The value of (BH)_<max> of the bonded magnet prepared from {Sm_<10>(Fe_<0.9>Co_<0.1>)_<89.5>Mn_<0.5>}_<84>N_<16> powder was 92.1 kJ/m^3 (11.6 MGOe) when the density of the bonded magnet was 6.05 Mg/m^3. The magnetization process of these nitrides is of the pinning-type. The reversible temperature coefficient of J_r was α(J_r)=-0.04%/℃ in the range from 25℃ to 125℃.
社団法人日本磁気学会の論文
2006-03-01