Optimizing low frequency electromagnetic parameters by controlling the distribution of boron in FeSiAl alloy

Abstract

Flaky FeSiAlB alloy powders were prepared by melting, quenching and milling. The effects of boron on the microstructure of FeSiAl alloy powders, the element distribution on the grain boundary of parent alloy, and the room temperature tensile properties of as-quenched sheet were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS) and tensile testing machine, respectively. With the addition of boron, the grain size of the master alloy was refined, and the tensile strength of the quenched sheet at room temperature was significantly improved. And obvious boron-rich regions were observed at grain boundaries. Soft magnetic properties were measured by vibrating sample magnetometer (VSM). Based on the electromagnetic parameters measured by vector network analyzer (VNA), the microwave absorption properties of flaky powder were calculated. The particles with high flake have high permittivity and permeability. Reflection loss (RL) shows that when B content amount was 0.06 at%, the absorption performance of the original FeSiAl absorbing material is improved in L and S bands, and the absorption peak moves from high frequency to low frequency. Excessive B element will lead to impedance mismatch, and the absorption performance in L and S bands will gradually decrease. For FeSiAlB flaky powder with 0.06 at % B content, the RL is −10.7 dB at 1.9 GHz and the matching thickness is 3 mm.