Sulfur-dissolved high-entropy alloys with ultrawide-bandwidth electromagnetic-wave absorption properties synthesized via a mechanochemical process

Further enhancing the effective absorption bandwidth (EAB) and the harsh-environment stability of high-entropy alloy (HEA) electromagnetic-wave absorbing (EMA) materials is of great practical significance and broad application prospects. A new type of sulfur (S)-dissolved HEA EMA material was developed in this work. The flaky FeCoNiCuSx (x = 0, 0.05, 0.10, 0.20) HEAs were successfully prepared by a mechanochemical process. The phase structure, magnetic properties, corrosion resistance, oxidation resistance and EMA performances of the FeCoNiCuSx HEAs were investigated in detail and it was found that the introduction of S significantly optimized the impedance matching and achieved excellent EMA performances. The results showed that S10 (FeCoNiCuS0.10) had a minimum reflection loss (RL) of -65.20 dB and a wide EAB of 6.89 GHz. And the S20 (FeCoNiCuS0.20) achieved an ultra-wide EAB of 7.00 GHz and an RL of -55.40 dB in the C-band. In addition, the FeCoNiCuSx HEAs also exhibited excellent corrosion resistance. This work not only demonstrated the potential application of S-dissolved HEAs in the EMA field in harsh environments, but also provided new ideas for optimizing the electromagnetic impedance matching of HEAs.