Microwedge indentation of the thin film fine line - II. Experiment

Experimental results of microwedge indentation are presented in order to evaluate the thin film fine line on a thick substrate as a fracture mechanics test specimen. Crack length is found to be proportional to indentation volume, allowing assessment of adhesion. The amplitude of single-buckles is used to estimate induced residual stress in the fine line and adhesion is independently assessed. The phenomena of double-buckling and spallation during indentation are experimentally verified, and are used to estimate fracture toughness of the thin film columnar grain boundaries. Although values of adhesion are unreasonably high, cracking of the substrate occurred, violating the critical assumption of negligible substrate compliance. The amplitude assessment gives a more reasonable value. A hypothesis for the complete sequence of events is proposed.