Improving the Soft Magnetic Characteristics of Nanocrystalline Soft Magnetic Composites Through the Incorporation of Ultrafine FeSiAl Powders

Nanocrystalline powders, characterized by a biphasic amorphous nanocrystalline structure, demonstrate outstanding soft magnetic characteristics, including reduced coercivity (Hc), enhanced effective permeability (μe), and increased resistivity. However, their high hardness, poor formability, and significant core loss (Pcv) restrict their use in high-performance molded inductors. In this study, FeSiBCuNb/FeSiAl nanocrystalline soft magnetic composites (NSMCs) were fabricated, and the influence of varying the FeSiAl concentration on the microstructure, density, and soft magnetic characteristics of NSMCs was investigated. Then, the underlying mechanisms of these effects were explained. The results demonstrate that FeSiAl exhibits apparent deformation following compression, effectively filling the air gap between the FeSiBCuNb powder particles, thereby enhancing coupling among the magnetic particles. Consequently, the density of the NSMCs was enhanced, leading to a significant improvement in their overall soft magnetic properties. When 50 wt.% FeSiAl is added, the NSMCs display outstanding magnetic properties, including a low Hc of 4.36 Oe, a high μe of 48.7, a low Pcv of 119.35 kW/m3 at 50 mT and 100 kHz, and a high DC-bias performance of 73.29% at 100 Oe. Compared to NSMCs without FeSiAl, μe increased by 59.4% and Pcv decreased by 66.1%. Meanwhile, the incorporation of ultrafine FeSiAl powder was found to significantly improve the material properties, as the deformable FeSiAl particles effectively fill interparticle gaps during compaction, enhancing density and magnetic coupling. The 50 wt.% FeSiAl composition demonstrated exceptional properties. These advances address critical challenges in high-frequency power electronic applications and provide a practical material solution for next-generation power electronics.