Abstract <p>As a typical electromagnetic wave absorption material, FeSiAl alloy material has high permeability and dielectric constant. The morphology of commercial FeSiAl alloy is closely related to the electromagnetic wave absorption properties, and structural optimization by changing the morphology of FeSiAl alloy could improve the electromagnetic wave absorption properties. In this paper, the phase composition, morphology, electromagnetic wave absorption properties and corrosion resistance of P120, P180 and P240 commercial FeSiAl alloys were studied. The results show that three kinds of FeSiAl alloys have a typical flake shape, and the phase composition is Fe₃Si_0.7Al_0.3, the permeability decreases with the decrease of the alloy particle size, and the absorption mechanism of the three alloys is dominated by the magnetic loss in the frequency band of 0–8 GHz. The small particles on the surface of FeSiAl alloy P120 are evenly distributed, and these small particles will promote the multiple reflection and scattering of electromagnetic wave on the surface of the alloy and improve the electromagnetic wave absorption performance. FeSiAl alloy P120 with optimal impedance matching and suitable attenuation coefficient. The FeSiAl alloy P120 shows a broad effective absorption band of 4.14 GHz at 40 wt % filler and a strong absorption peak of –39.0 dB in the 4.5 GHz frequency range, matching a thickness of 5.0 mm. In addition, among the three FeSiAl alloys, P240 has the largest polarization resistance and the best corrosion resistance. Fe₂O₃, Al₂O₃ and SiO₂ were formed by chemical reaction of FeSiAl alloy P120 after corrosion. The content of iron is the most and the corrosion is the most serious. After corrosion, pits and gullies appear on the surface of the alloy, which reduce the electromagnetic wave absorbing properties of the alloy. The optimal reflection loss value of FeSiAl alloy p120 after corrosion is only –20.9 dB, and the effective bandwidth is 2.61 GHz.</p>