Revision as of 12:12, 1 July 2024

Abstract

High entropy alloys (HEAs) especially CoCrFeMnNi HEAs have drawn more and more attention due to their excellent combination performance. However, the mechanical properties of CoCrFeMnNi HEAs still remain to be improved due to the single-phase FCC crystal structure. Although many efforts have been made on strengthening methods by grain refinement or nitriding the improvement of the mechanical properties is still unsatisfactory. To improve the mechanical properties of CoCrFeMnNi HEAs and broaden their application fields, we proposed that adding functionalized graphene in CoCrFeMnNi HEAs and investigated nanoscale mechanical properties and the strengthening mechanism using molecular dynamics (MD) simulation in this paper. The mechanical properties of pristine single-layer graphene nanoplatelets (GNPs) and double-side nickel-coated GNP (Ni-GNP-Ni) reinforced CoCrFeMnNi composites (Ni-GNP-Ni/CoCrFeMnNi) are studied under uniaxial tension by molecular dynamics (MD) simulations. The simulated results show that the mechanical properties of Ni-GNP-Ni/CoCrFeMnNi composites are improved significantly by the addition of Ni coated GNPs. The mechanical properties of Ni-GNP-Ni/CoCrFeMnNi composites exhibit temperature softening and strain rate strengthening effect, and their tensile mechanical properties such as the tensile strength, fracture strain decrease with increasing temperature and enhance with increasing strain rate. It is concluded that the main strengthening mechanisms for Ni-GNP-Ni/CoCrFeMnNi composites are strong interface bonding, effective load transfer from the CoCrFeMnNi matrix to the Ni-GNP-Ni and dislocation/twin strengthening by analysis of the evolution of atomic structure.