Enhanced microwave absorption performances of onion-like carbon coated FeNiCoCuTi high-entropy alloys nanocapsules

High entropy alloys (HEAs), a new type of functional material, are rarely applied to prepare core-shell structured nanocomposites. In this work, FeCoNiCuTi@C nanocapsules have been prepared by arc discharging HEAs ingot under the atmosphere of methane, displaying the sphere shape with the average diameter of 72.1 nm and ~ 3 nm onion-like carbon shell and the single FCC phase. The melting points, crystal structure and electronegativity play the important role on determining the element composition and atomic percentage. Carbon facilitates protecting magnetic elements, improving EM parameters and enhancing resonance frequency. Good impedance matching, strong electromagnetic loss ability and large attenuation constant ensure the microwave can enter the nanocapsules to the largest extent and could be consumed. These advantages provide the basis for the excellent microwave absorption performance ( effective bandwidth of 5.52 GHz at 1.9 mm, maximal reflection loss of −37.78 dB and absorption efficiency of 52.41 dB·GHz/mm at 1.8 mm) of FeCoNiCuTi@C nanocapsules. • FeNiCoCuTi high-entropy alloys nanocapsules with onion-like carbon are prepared. • Core/shell structure leads to good impedance matching, strong attenuation and loss. • Effective bandwidth is 5.52 GHz at 1.9 mm and absorbing efficiency is 52.4 dB GHz/mm.