Abstract
An experiment was carried out to examine the effect of composition, heat treatment, and nitrogenation conditions on the magnetic properties of Sm-Fe-Co-Ti-Zr nitrides with TbCu7-type structure. The optimum preparation conditions of the compounds were as follows: composition {Sm10(Fe0.9Co0.1)89.2Ti0.3Zr0.5}83.5N16.5; roller velocity 52m/s; heat treatment 700°C × 60 min in high-purity Ar gas; and nitrogenation condition 420°C × 15 h in high-purity N2 gas. Typical magnetic properties of the obtained powders were as follows: Jr = 0.96 T, HcJ = 811.7 kA/m, (BH)max = 141 kJ/m3 (17.7 MGOe), and Tc = 504°C. 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 {Sm10(Fe0.9Co0.1)89.2Ti0.3Zr0.5}83.5N16.5 powder was 102 kJ/m3 (12.8 MGOe) when the density of the bonded magnet was 6.06 Mg/m3. The reversible temperature coefficient of Jr was α(Jr)ave. = −0.05 %/°C, and the temperature coefficient of HcJ in the range from 25°C to 125°C obtained by linear extrapolation was α(HcJ) = −0.46 %/°C
