Abstract
Experiments were carried out to investigate the effect of composition, heat-treatment and nitrogenation conditions on the magnetic properties of Sm-Fe-Co-Ti-N compounds with TbCu7-type structure. The optimum preparation conditions of the compounds were as follows: composition: {Sm10(Fe0.95CO0.05)89.7Ti0.3}82.0N18.0, roller velocity: 50 m/s, heat treatment: 680°C for 60min in high-purity Ar gas, and nitrogenation condition: 420°C for 15h in high-purity N2 gas. Typical magnetic properties of the obtained compound powders were as follows: Jr=0.99 T, Hcj=736.5 kA/m, HcB=540.4 kA/m, (BH)max=140.9 kJ/m3 (17.7 MGOe), and Tc=488°C. It was found that this sample was an exchange spring magnet from recoil loops of the hysteresis curve, TEM photographs and X-ray analysis. The value of (BH)max for the compression-molding isotropic bonded magnet prepared by using from {Sm10(Fe0.95Co0.05)89.7Ti0.3}82.0N18.0 powder was 103.2 kJ/m3 (13.0 MGOe), when the density of bonded magnet was 6.04 Mg/m3. And the average reversible temperature coefficient of Jr was a(Jr)ave.=-0.04%/°C, the temperature coefficient of Hcj in the range from 25°C to 125°C obtained by a linear extrapolation was a (HcJ) =-0.44 %/°C.
