Excellent electromagnetic-wave absorbing performances and great harsh-environment resistance of FeCoNiCrxMn high entropy alloys

FeCoNiCrxMn (x = 0.0, 0.6, 0.8, 1.0) high-entropy alloys (HEAs) were prepared by a 3D high-energy ball-milling method. The phase structure, grain size, crystallinity, morphology, static magnetic properties, corrosion resistance, oxidation resistance and electromagnetic properties of FeCoNiCrxMn HEAs are investigated in detail by modulating Cr contents. FeCoNiCrxMn HEAs had the phase transformation from FCC to BCC with the increase of Cr contents, which caused abnormal change of both static magnetic properties and corrosion resistance. The introduction of Cr is beneficial to improve the corrosion resistance and oxidation resistance of the alloys. In addition, FeCoNiCrxMn HEAs had excellent electromagnetic-wave absorption performances. The minimum reflection loss (RLmin) of FeCoNiCr0.6Mn reached − 66.9 dB at 4.9 GHz with a thickness of 2.8 mm, and FeCoNiCr0.8Mn had the RLmin of − 57.4 dB at 5.2 GHz with a thickness of 3.3 mm. This study shows that FeCoNiCrxMn HEAs have practical application prospect due to the excellent electromagnetic-wave absorbing performances and great harsh-environment resistance.