Molecular dynamics simulation of nanoindentation on amorphous/amorphous nanolaminates

The nanoindentation deformation behaviors of Cu₈₀Zr₂₀ (A)/Cu₂₀Zr₈₀ (B) amorphous/amorphous nanolaminates were studied by using molecular dynamics (MD) simulation, aiming to investigate the effects of heterogeneous interface and layer thickness on the hardness. It was found that there is a strong length-scale-dependence for the mechanical properties of amorphous/amorphous nanolaminates. There is a critical range of layer thickness h (~1 nm < h < 2 nm), within which the hardness of nanolaminates is minimized. By analyzing the shear strain and atomic displacement vector, the interface strengthening effect was found to be prominent when the layer thickness is less than 1 nm. We also revealed that the hardness of nanolaminates is mainly contributed by the surface layer when the layer thickness is larger than 1 nm, which should not be ignored when evaluating the mechanical properties at nanoscale. The current work highlights the influence of interface on the shear localized deformation through MD simulations, and shows that the amorphous/amorphous nanolaminates could be an important candidate for high performance materials at room temperature.