Sintered SrFe12O19/Fe–B composites: Precipitation of α-Fe and magnetic properties

SrFe12O19 (SrM) and Fe–B powders obtained via a hydrothermal and a molten salt method, respectively, were uniformly mixed with different mass ratio (Rm) and sintered at different sintering temperatures (Ts), attempting to prepare SrM/Fe–B composites. The structural and magnetic properties of sintered composites are systematically studied. It is found that the composite only consists of SrM and Fe–B powders after sintering at 500 °C. However, the precipitation of α-Fe begins after sintering at a temperature of 600 °C, and attains the severest at about 690 °C. Both the saturation magnetization and coercivity of composites change irregularly with the increase of Rm, while they keep a marked increasing and decreasing tendency, respectively, with the increase of Ts. All the above changes of magnetic properties could be ascribed to the precipitation of α-Fe and the formation of new phase(s).