Enhanced Microwave Absorption of Al-Based Multi-Principal Element Solid-Solution Alloy/Carbon Nanofibers via Synergistic Effects

The rapid advancement of communication technology has heightened concerns over electromagnetic pollution. Developing absorptive materials with dual-loss mechanisms through dielectric and magnetic loss integration offers an effective solution for impedance matching and interference reduction. Herein, Al-based FeCoNiAl multi-principal element solid-solution alloy-decorated carbon nanofibers (FeCoNiAl/CNFs) were synthesized via electrospinning and carbothermal reduction. This system, with a designed molar ratio of 1:1:1:10 (Fe:Co:Ni:Al), strategically leverages the high aluminum content to tailor electromagnetic functionality. The Al matrix actively down-regulates conductivity to optimize impedance matching, while the FeCoNi combination ensures strong and tunable magnetic loss. This design achieves a unique synergy of lightweight character, strong attenuation, and enhanced stability, all underpinned by the formation of a single solid-solution phase, as confirmed by XRD analysis showing three strong diffraction peaks without impurities. At an optimal reduction temperature of 1000 °C, the FeCoNiAl/CNFs composite exhibits a minimum reflection loss (RL min ) of –25.0 dB at 6.08 GHz and an effective absorption bandwidth (EAB) of 2.16 GHz (5.04–7.20 GHz) at a matching thickness of 3.0 mm. The superior performance originates from synergistic dielectric polarization, magnetic resonance, and optimized impedance matching enabled by the tunable Al-based solid-solution alloy. This work provides a novel and rational strategy for designing lightweight, stable, and high-performance microwave absorbers with industrial applicability.