Interfacial characteristics and their impact on the indentation behavior of CuTa/CuTa amorphous/amorphous nanolaminates

The mechanical characteristics and deformation mechanisms of Cu80Ta20/Cu20Ta80 amorphous/amorphous nanolaminates under the nanoindentation are still unclear. In this study, the influences of layer thickness and interface on the indentation behavior of nanolaminates are systematically investigated using molecular dynamics simulation. Moreover, the effects of indenter size, loading velocity, and surface layer on the deformation mechanism of nanolaminates are also clarified. The important results expose a strong dependence on the layer size for the mechanical properties of nanolaminates. The hardness of nanolaminates is maximized for a specimen with a layer thickness of 17.5 angstrom. Besides, the hardness decreases with increasing the indenter radii due to the indentation size effect, and the hardness increases as the increase of loading velocity. The plastic deformation behavior displays that the interfaces play a significant role in obstructing the expansion of the plastic deformation region from the indentation into the interior of workpiece. Furthermore, the elastic recovery is highest for the sample with the smallest layer thickness of 5.0 angstrom, and the elastic recovery tends to increase with increasing the indenter radius and decreasing the loading velocity. The influence of surface layer shows that the interfaces dominate the deformation mechanism for specimens with small-layer thickness, while the surface layer controls the indentation behavior of nanolaminates with large-layer thickness.