Creep crack propagation behavior in submicron gold films

AbstractCreep crack propagation experiments on Au freestanding films of ˜240 nm and ˜390 nm thickness at room temperature were conducted to clarify the creep crack propagation properties and the thickness effects. In all the experiments, cracks stably propagated and the propagation was accompanied by creep deformation. The crack propagation rate da/dt was not uniquely characterized by the stress intensity factor. The steady-state creep J-integral J*s was estimated by an approximate equation using the experimental crack center opening displacement rate. The creep crack propagation rate da/dt vs. J*s relations were observed within a narrow band irrespective of the specimen width and applied stress, indicating that J*s was the dominant mechanical parameter of the creep crack propagation rate in the Au films. Furthermore, the da/dt–J*s relations were close to each other in the ˜240 nm and ˜390 nm films, suggesting that the creep crack propagation properties of the Au films were insensitive to the film thickness in the thickness range of from ˜240 nm to ˜390 nm