Effect of sintering temperature on the structure and magnetic properties of SmCo5/Fe nanocomposite magnets prepared by spark plasma sintering

Highly dense SmCo5/Fe nanocomposite bulk magnets were prepared by spark plasma sintering of magnetic field-milled SmCo5/Fe nanocrsytalline powders. The sintering experiments were conducted with varying temperatures of 973–1123 K. The resultant bulk materials had densities of 85–98% and mean grain sizes of 17–30 nm. The SEM analysis showed that the bulk samples prepared at higher sintering temperature exhibited dense and uniform microstructure. The XRD studies in complement with energy dispersive X-ray analysis revealed that the bulk magnets sintered at or above 1073 K exhibited Sm(Co,Fe)5 as main phase, along with other secondary phases such as Sm2(Co,Fe)17 and α-Fe(Co). A single-phase behavior with high remanence ratios (0.67–0.77) for the nanocomposite magnets was demonstrated by the magnetic measurements. In the present study, the sintering temperature of 1073 K was found to be optimum in achieving relatively high coercivity (8.2 kOe), magnetization (97.5 emu/g) and energy product (278.7 kJ/m3) for the SmCo5/Fe nanocomposite bulk magnets.