Improving interfacial magnetoelastic effect and complex permeability of FeSiAl alloy powders for broadband decimeter-wave absorption via Cr doping

This study showcases the interfacial magnetoelastic effect observed in flaky FeSiAl alloy powder absorbents, aimed at enhancing permeability in the decimeter-wave band for better absorption performance through Cr doping via wet ball-milling and subsequent annealing processes. The wet ball milling process facilitates the formation of a lamellar structure by inducing slip along shear stress in DO ₃ and α-Fe nanocrystals. During annealing, the introduced Cr element partially impedes the transition from the α-Fe phase to the DO ₃ phase, thereby amplifying the difference in magnetostrictive coefficients between these phases. Consequently, the flaky FeSiAlCr powders exhibit notably increased initial permeability and resonance frequency, particularly around 3 GHz, owing to domain rotation in the DO ₃ phase. In comparison to previously reported counterparts, the composite derived from these powders demonstrates a significant enhancement in the real part of effective permeability by approximately 66 %, alongside a 17 % reduction in density. Consequently, this composite exhibits a lowered reflection loss of below −5 dB within the frequency range of 0.7–3 GHz, reaching a minimum of −11 dB at 1.57 GHz, specifically with a thickness of 1.6 mm. These findings present an effective strategy for enhancing the magnetic permeability of alloy powders. The resultant microwave absorbing materials hold promising applications in stealth technology and wireless communication electronics.