In situ observation on creep crack propagation mechanisms of Au submicron films

Abstract

To clarify the creep crack propagation mechanisms of Au submicron films, a creep crack propagation experiment is conducted for a 359-nm-thick Au freestanding film with a center notch under in situ FESEM observation. The notch root largely blunts and then a crack is initiated at the blunted notch root. A few voids nucleate ahead of the crack tip and the main crack propagates by coalescence of the crack and the voids. In the early stage where creep crack propagation rate is low, creep damage around the crack tip is confined to a small region less than 1-2 μm. In the later stage, creep damage spreads over a larger distance, resulting in the slower creep crack propagation rate.