Low core loss, corrosion-resistant soft magnetic composites fabricated via powder atomic layer deposition

As third-generation semiconductors advance toward higher frequencies, soft magnetic composites (SMCs) for extreme conditions require concurrent low-loss properties and environmental stability. The Fe-Cr-Si-B-C alloy offers inherent corrosion resistance over other soft magnetic alloys but requires modification for salt spray environment. Insulating coatings are critical for SMCs to meet high-frequency demands. Here, Fe-Cr-Si-B-C powder, engineered via powder atomic layer deposition (PALD), are coated with a nanoscale amorphous Al 2 O 3 layer that provides electrical insulation, physical separation, and enhanced environmental stability while maintaining minimal loss. The PALD-modified SMCs achieve a core loss of 433.3 mW/cm 3 (20 mT, 1 MHz) and 99.7 % corrosion inhibition efficiency. This work proposes a design strategy for high-frequency SMCs combining low loss and extreme environmental durability.