Subsurface nanoindentation deformation of Cu-Al multilayers mapped in 3D by focused ion beam microscopy

A new technique for the three-dimensional analysis of subsurface damage of nanocomposites is presented. Cu-Al multilayers, grown epitaxially on (0001)Al2O3 single crystals by ultra high vacuum molecular beam epitaxy, have been deformed by nanoindentation. Systematic slicing and imaging of the deformed region by focused ion beam microscopy enables a 3D data set of the damaged region to be collected. From this 3D data set, profiles of the deformed sub-surface interfaces can be extracted. This enables the deformation of the individual layers, substrate and overall film thickness to be determined around the damage site. These 3D deformation maps have exciting implications for the analysis of mechanical deformation of nanocomposites on a sub-micrometre scale.