Microstructure and magnetic properties of Sm2Fe17Nx compound and their magnets prepared by field-activated combustion

The microstructure and properties of isotropic Sm2Fe17Nx powder and their magnets prepared by field-activated combustion at 400–500 °C were investigated by XRD, SEM and EDXS methods. The results show that there is a small fraction volume of H atom left in the sample after the HDDR process at 775 °C, and the powder nitridinged at 500 °C for 5 h is nearly composed of single Sm2Fe17Nx phase. During the field-activated pressure-assisted synthesis (FAPAS) process, the Sm2Fe17Nx compounds partly decomposed into SmN and α-Fe phases. With increase of temperature, the effect of sintering gets better and the obtained density is larger, but the magnetic property is decreased. The best magnetic property of isotropic Sm2Fe17Nx magnet is obtain at 450 °C, which is Br = 0.660 T, Hcj = 1006 kA/m, (BH)max = 72 kJ/m3.