Understanding the extremely low fracture toughness of freestanding gold thin films by in-situ bulge testing in an AFM

The fracture toughness of freestanding gold films with thicknesses between 60 nm and 320 nm was determined by bulge testing to be around 2 MPa m1/2. This surprisingly low value confirms the trend also observed for other metals that thin films exhibit only a fraction of the bulk fracture toughness. In order to understand this behavior, the fracture process of freestanding gold films with a crack introduced by focused ion beam (FIB) milling was...