TbCU_7型Sm-Fe-Co-W-Cr系窒化化合物の磁気特性

概要

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Experiments were carried out to investigate the magnetic properties of Sm-Fe-Co-W-Cr system nitriding compounds with TbCu7-type structure. Sm10(Fe0.95Co0.05)89.7-xW0.3Crx (x =0-0.7) alloy ribbons were prepared by the single roller rapid-quenching method, and the effects of alloy composition, and conditions of heat-treatment and nitrogenation, were examined with regards to their magnetic properties. The optimum preparation conditions of the compounds are as follows. Composition: {Sm10(Fe0.95Co0.05)89.4W0.3Cr0.3}85.0N15.0, roller velocity: 50m/s, heat treatment: 675 °C×60 min in high-purity Ar gas, and nitriding condition: 420 °C×10 h in high-purity N2 gas. Typical magnetic properties of the obtained compound powders areσr =123.7×10-6 Wb·m/kg, HcJ =706.0 kA/m, (BH)max =139.4 kJ/m3 (17.4 MGOe), and Tc =508 °C. It was found that this sample was an exchange spring magnet from TEM photographs and recoil loops of the hysteresis curve. The value of (BH)max for the compression molding isotropic bonded magnet prepared from the {Sm10(Fe0.95Co0.05)89.4W0.3Cr0.3}85.0N15.0 powder is 102.9 kJ/m3 (12.9 MGOe), when the density of bonded magnet is 6.1 Mg/m3. And the reversible temperature coefficient of Jr is α(Jr) =-0.07 %/°C, the temperature coefficient of HcJ in the range from 25 °C to 125 °C obtained by a linear extrapolation is α(HcJ) =-0.44 %/°C.
社団法人電気学会の論文
2003-06-01