Abstract
Experiments were carried out to investigate the effects of composition, heat-treatment and nitrogenation conditions on the magnetic properties of Sm-Fe-Co-Cr-Y-N compounds with the TbCu7-type structure. The optimum preparation conditions of the compounds were as follows: composition: {Sm10(Fe0.9Co0.1)89.4Cr0.3Y0.3}86.6N13.4, roller velocity: 50 m/s, heat treatment: 680°C for 60 min in high-purity Ar gas, and nitrogenation condition: 420°C for 10 h in high-purity N2 gas. Typical magnetic properties of the obtained compound powders were as follows: Jr=0.98 T, HcJ=765.1 kA/m, HcB=545.4 kA/m, (BH)max=138.5 kJ/m3 (17.4 MGOe), and Tc=523°C. It was found that this sample was an exchange spring magnet from recoil loops of the hysteresis curve, X-ray diffraction patterns and σ-T (Magnetization-Temperature) curve. The value of (BH)max for a compression-molded isotropic bonded magnet prepared by using {Sm10(Fe0.9Co0.1)89.4Cr0.3Y0.3}86.6N13.4 powder was 96.2 kJ/m3 (12.1 MGOe), when the density of bonded magnet was 6.05 Mg/m3. And the average reversible temperature coefficient of Jr was α(Jr)ave.=−0.05 %/°C, the temperature coefficient of HcJ in the range from 25°C to 125°C obtained by a linear extrapolation was α (HcJ)=−0.40 %/°C.
