Multi-element co-penetration engineering in high-entropy alloys for efficient electromagnetic-wave absorption†

High entropy alloys (HEAs) show great potential in electromagnetic-wave absorption (EMA), but impedance matching and environmental stability are still difficult problems to solve. Solid-solution strengthening is an effective means to enhance the performances of EMA materials. The multi-element co-penetrated FeCoCrMn HEAs are prepared using urea (CH₄N₂O) as the multi-element source by a green mechanochemical approach. The phase structure, magnetic properties, corrosion and oxidation resistance, and EMA properties of HEAs are investigated in detail. The results show that the crystal structure of HEAs is significantly altered by multi-element introduction. It is noteworthy that M_s is significantly enhanced on increasing the multi-element co-penetration level. The dielectric loss and magnetic loss of HEAs are significantly enhanced to optimize the impedance matching and attenuation properties, so as to achieve excellent EMA performances. Multi-element co-penetrated FeCoCrMn HEAs achieve a reflection loss (RL) of −59.6 dB at 6.06 GHz while achieving an ultra-wide effective absorption bandwidth (EAB) of 6.86 GHz at 1.32 mm. In addition, HEAs exhibit excellent corrosion resistance, indicating suitability in harsh environments. This study provides a new strategy for the design of highly effective EMA materials.