Molecular Dynamics Simulation for Nanoindentation on Nano-Laminated Dual-Phase CoCrFeMnNi High-Entropy Alloy

Single-crystal face-centered cubic high-entropy alloys (SCF-HEAs) CoCrFeMnNi have gained considerable interest because of their excellent mechanical properties. It is believed that building a proper nano-laminated dual-phase (DP) FCC/HCP structure is one of the most promising strategies to further improve the strength of HEAs. However, the relationship between atomic evolution and its mechanical properties is still unclear. In this work, the mechanical responses of the DP CoCrFeMnNi HEA samples under nanoindentation were investigated using molecular dynamics (MD) simulations. It was found that the indentation depth related to the initiation of plastic deformation in DP-HEA is different from that in SCF-HEA, and the hardness of the former is higher than that of the latter, but lower than that of the HCP structured HEA (SCH-HEA). The relationship between the hardness and dislocation density was described with the Taylor hardening model, and the strengthening effect of the FCC/HCP interface was also compared with that of the twin boundary. The current work could provide insight into the microstructural and interfacial deformation of the DP-HEA, which would help to optimize the strength and plasticity of the HEA composite.