Effects of an elastic substrate on the interfacial adhesion of thin films

Nanoindentation is a powerful technique for measuring the mechanical properties of materials such as elastic modulus, hardness, fracture toughness and interfacial adhesion, especially for some structures in micron thickness. Conventional nanoindentation techniques produce large plastic deformation directly affecting the elastic properties to be measured. As compared to conventional nanoindentation, the cross-sectional nanoindentation lowers the influence of plastic deformation on measured elastic properties, and measured data are more reliable. For the cross-sectional nanoindentation, a modified theoretical model based on the elastic plate theory with elastically restrained edges is presented to evaluate the energy release rate of an interfacial delamination between a thin film and an elastic substrate. A closed-form solution is given and the predicted interfacial adhesion is in satisfactory agreement with existing experimental data.