Electromagnetic interference shielding effectiveness of high entropy AlCoCrFeNi alloy powder laden composites

The electromagnetic interference (EMI) shielding effectiveness of epoxy based composite samples, containing two different sizes of high entropy AlCoCrFeNi alloy powders, was examined under Kα band [26-40 GHz] in this paper. High-energy ball milling processes were used to fabricate AlCoCrFeNi alloy powders of two different sizes, HEAL for larger sizes and HEAS for finer powders, respectively. Comparing with the 8.44 dB value of the HEAL containing sample, the HEAS sample has a maximum total shielding effectiveness (SET) of 20 dB due to the smaller powder sizes and flake-like morphology. Shielding mechanism was studied by resolving the total EMI SET into absorption and reflection portions. Absorption was found to be the major shielding mechanism and reflection had a secondary shielding effect for both HEAL and HEAS cases.