High-frequency FeSiAl-based soft magnetic composites via simultaneously suppressed eddy and hysteresis losses.

Li, Hongxia; Li, Yixing; Zhao, Rongzhi; Bandaru, Sateesh; Zhang, Zhenhua; Pan, Hong; Lin, Jintao; Liu, Zhaoyuan et al. · Nat Commun · 2025

basic_science · Level V

Where this comes from

Abstract

Soft magnetic composites present promising solutions for integrated transformers and inductors, but challenges arise at MHz range, where hysteresis and intra-eddy losses result in substantial performance degradation. In this study, we propose a bulk/interface insulation strategy to synthesize FeSiAl:Sn/Al<sub>2</sub>O<sub>3</sub> soft magnetic composite by mutual diffusion of metal atoms, where a ~ 3 um-depth Sn-substituted FeSiAl is obtained in the matrix and an insulating Al<sub>2</sub>O<sub>3</sub> layer is epitaxially grown on FeSiAl surface. The formation of FeSiAl:Sn can not only suppress intra-eddy loss by enhancing electrical resistivity, but also reduce coercivity by mitigating lattice distortion for reducing hysteresis loss. Meanwhile, the in-situ grown Al<sub>2</sub>O<sub>3</sub> layer can reduce inter-eddy loss by electrical isolation between FeSiAl particles. This construction leads to power loss of 47 mW/cm<sup>3</sup> at 100 kHz and 1344 mW/cm<sup>3</sup> at 1 MHz under 50 mT, as well as effective permeability of 60 up to tens of MHz, associated with cut-off frequency of 250.7 MHz. This approach lays the groundwork for the development of high-frequency soft magnetic composites in engineering applications.