Microstructure and Magnetic Properties of Grain Boundary Insulated Fe/Mn(0.5)Zn(0.5)Fe(2)O(4) Soft Magnetic Composites

Mn(0.5)Zn(0.5)Fe(2)O(4) nano-powder was coated on Fe microparticles by mechanical ball milling combined with high-temperature annealing. The effects of milling time on the particle size, phase structure and magnetic properties of core–shell powder were studied. Scanning electron microscopy (SEM), energy-dispersive spectroscopy and X-ray diffraction showed that the surface of the milled composite powder was composed of thin layers of uniform Mn(0.5)Zn(0.5)Fe(2)O(4) insulating powder. SEM also revealed a cell structure of Fe particles, indicating that the Fe particles were well separated and isolated by the thin Mn(0.5)Zn(0.5)Fe(2)O(4) layers. Then, Fe/Mn(0.5)Zn(0.5)Fe(2)O(4) soft magnetic composites were prepared by spark plasma sintering. The amplitude permeability of Fe/Mn(0.5)Zn(0.5)Fe(2)O(4) SMCs in the Fe/Mn(0.5)Zn(0.5)Fe(2)O(4) soft magnetic composites was stable. The resistivity decreased with the increase in sintering temperature. The loss of the composite core was obviously less than that of the iron powder core. Hence, the preparation method of Mn(0.5)Zn(0.5)Fe(2)O(4) insulating iron powder is promising for reducing core loss and improving the magnetic properties of soft magnetic composites.