Excellent electromagnetic wave absorption performances of FeCoNiAlTix high-entropy alloys with superior oxidation resistance†

The rapid advancement of electromagnetic wave (EMW) technology has significantly increased the military's demand for anti-reconnaissance measures and the need to mitigate electromagnetic interference in daily life. High-entropy alloys (HEAs) have garnered widespread attention as a new generation of absorbers due to their tunable EMW absorption properties and strong stability. Among them, FeCoNiAl-based HEAs are known for their strong magnetic loss capabilities and moderate oxidation resistance, which are critical for the regulation of microwave absorption performance and adaptation to high-temperature environments. However, limitations such as a narrow effective absorption bandwidth (EAB), a narrow slow-oxidation temperature range, and relatively high density have been reported in current studies. In this work, as a lightweight and corrosion-resistant element with a large atomic radius and low valence electron count, Ti was introduced to induce a phase transformation of the alloy structure toward a BCC phase with superior magnetic loss capabilities, while reducing density and improving oxidation resistance. FeCoNiAlTi_0.6 prepared via high-energy ball milling exhibits excellent EMW absorption performance and oxidation resistance, achieving the minimum reflection loss (RL_min) of −66.38 dB with a thickness of 1.68 mm, and the widest EAB of 6.11 GHz, covering a slow oxidation temperature range of 0 to 900 °C.