Microstructure and performances of FeBSiPCNbCu/FeNi soft magnetic composites and molded inductors

Driven by growing terminal markets, molding inductors are advancing toward higher frequencies, miniaturization, and higher currents capacities, with Fe-based nanocrystalline alloys serving as ideal high-frequency materials. While their high hardness reduces the compactness of soft magnetic composites (SMCs), this limitation is mitigated by compounding with small-sized FeNi powders owing to their superior properties. In this work, FeBSiPCNbCu/FeNi soft magnetic composites were fabricated by blending large-particle nanocrystalline powder with small-sized FeNi powder. The effects of FeNi content on the magnetic and mechanical properties were systematically investigated. Results indicate significant improvements at 70 wt% FeNi powder, the corresponding magnetic powder core exhibited an impressive effective permeability of 27, a saturation magnetic induction intensity of 1.16 T, and a low core loss of 900.4 mW/cm 3 (20 mT, 2 MHz). In contrast, the core without FeNi powder exhibited values of 16.8, 0.94 T, and 3140.4 mW/cm3, respectively. Additionally, the radial crushing strength was enhanced by 103.7%, increasing from 143.1 to 291.5 MPa. Finally, a production verification test was conducted on the fabricated molding inductors, which demonstrated excellent performance: a DC resistance of 2.01 mΩ, a saturation current of 40 A, and a temperature rise current of 21 A, respectively. These findings demonstrate the significant potential of this material system for practical production applications.