Atomistic simulation and experimental verification of tribological behavior of high entropy alloy/graphene composite coatings

Dissatisfactory yield strength and wear have been critical issues in FCC single phase high entropy alloy (HEA) limiting wide applications as advanced engineering materials, in spite of their attractive mechanical and physical properties. Here we show by introducing graphene layer, the tribological properties of Fe₂₀Ni₂₀Cr₂₀Co₂₀Cu₂₀/graphene composite coatings can be noticeably enhanced. In this work, molecular dynamics simulations were performed to probe the tribological mechanisms of HEA/graphene composite coatings. It was revealed that the reasonable choice of single-layer graphene geometry and embedding position play an important part in friction reduction and anti-wear of the coatings. The graphene interface not only cause robust dislocation blockage from HEA, but also reduces the accumulation of atoms at surface during sliding. Besides, the influence of temperature on the tribological behavior of the coatings is explored. The tribological performances of the coatings were also investigated by the experimental nanoscratch test, which are consistent with the simulation results. The present work provides a theoretical and technical support for the design of wear-resistant self-lubricating coatings, promoting the engineering applications of HEA coating materials.