Interfacial structure design of FeSiB-based amorphous soft magnetic composites for excellent thermal stability and electromagnetic performance

Narrow process window of stress relieving annealing limits the development of amorphous soft magnetic composites (SMCs) with excellent combined electromagnetic performance. In addition, flaky amorphous powder is difficult to be uniformly coated by insulation layer due to the edge effect. To address these issues, the FeSiBCCr fine amorphous powder is introduced into the SMC based on flaky FeSiB amorphous powder. On the one hand, the 12 wt% addition of FeSiBCCr powder improves the thermal stability and enhances the annealing temperature by ∼ 20 ℃, broadening the annealing window of SMCs. On the other hand, the fine spherical FeSiBCCr amorphous powder can improve the electrical resistivity of SMC and act as a filler for large-size flaky FeSiB amorphous powder. The improved annealing temperature and the microstructure modification are beneficial to improving the combined electromagnetic properties of amorphous SMCs, including permeability, direct current bias performance and core loss. As a result, the FeSiB SMCs with 12 wt% FeSiBCCr addition possess the high effective permeability μ_e of 46.5 at 100 kHz, high percent effective permeability %μ_e of 74.5 % at 100 kHz and 100 Oe, and low total core loss of 222 kW/m³ at 100 kHz and 50 mT. This work proposes a potential strategy for the industry to fabricate the SMCs with high combined electromagnetic performance.