Soft magnetic composites (SMCs) based on Fe–Si–Cr (FeSiCr) are attractive for molded power inductors but can suffer from elevated core loss at high frequency. In this work, FeSiCr/phenolic SMCs are systematically benchmarked by blending the FeSiCr–phenolic matrix (2 wt%) with three insulated, fine iron powders—silica-coated reduced iron powder (RIP), silica-coated carbonyl iron powder (CIP), and phosphate-treated CIP (CIP-P)—across 10–50 wt% and against single-powder baselines. Toroids pressed at 200 MPa and cured at 150 °C were characterized for permeability μ(f) (100 kHz–1 MHz), B–H loss at 50 mT, DC-bias retention (15 A on T-cores), corrosion (salt spray), and microstructure via EBSD kernel average misorientation (KAM). A clear structure–property linkage emerges: higher KAM and low-angle boundary (LAGB) fractions correlate with higher coercivity and hysteresis loss, providing a quantitative microstrain–core loss descriptor. Blending exhibits a pore-filling optimum. For CIP/CIP-P, this occurs at ~ 20–30 wt%, maximizing permeability and minimizing hysteresis. For RIP, the permeability optimum is at ~ 10 wt%, while the minimum for hysteresis loss and coercivity occurs at ~ 30 wt%. Eddy-current loss reductions are strongest with silica-coated CIP/RIP; the phosphate interface (CIP-P) gives less high-frequency benefit. Under 15 A DC bias, all additives improved inductance retention compared to the FeSiCr baseline. The blends ranked in the order of RIP ≈ CIP ≫ CIP-P > FeSiCr, with RIP and CIP performing similarly at low-to-moderate loadings. This improvement reflects the higher Ms of iron powders and the favorable EBSD metrics of RIP at low loading. Corrosion tolerance follows RIP ≈ CIP ≫ CIP-P, with mold-edge abrasion acting as the primary initiation site. Incorporating recycled RIP advances circular-economy goals while delivering best-in-class bias stability with competitive core loss when used near its pore-filling window.
Yang et al. (Sun,) studied this question.