Microstructure and magnetic properties of Fe–6.5 wt.% Si/MnZn(Fe₂O₄)₂ composites with core-shell structure prepared by spark plasma sintering

Fe–6.5 wt.% Si powder coated with 10 wt.% MnZn(Fe₂O₄)₂ (MnZn ferrite) was successfully prepared by using dry-type stirring ball milling. The Fe–6.5 wt.% Si/MnZn(Fe₂O₄)₂ soft magnetic composites were prepared by subsequent spark plasma sintering. This paper aims at analyzing the microstructure and magnetic properties of Fe–6.5 wt.% Si/MnZn(Fe₂O₄)₂ soft magnetic composites (sintering temperature: 750${}^{\circ }$C, sintering pressure: 50 MPa, holding time: 8 min, heating rate: 60 K/min). Based on X-ray diffraction and scanning electron microscopy, microstructure and powder morphology were examined and magnetic measurements on bulk samples were conducted by vibrating sample magnetometer and impedance analyzer. According to the experiments results, Fe–6.5 wt.% Si/MnZn(Fe₂O₄)₂ composites displayed a core-shell structure, and ceramic phase was observed after sintering. The Fe–6.5 wt.% Si/MnZn(Fe₂O₄)₂ composites achieved high resistivity ($\rho :2.9$ m$\mathrm{\Omega }$/cm) while maintaining excellent magnetic properties ($M_s:174.00$ emu/g). Core losses especially at medium and high frequencies were significantly reduced.