Ultra Low Cycle Fatigue of Axisymmetric Freestanding Nanoscale Gold Films

We present ultra low-cycle fatigue experiments of axisymmetric nano-crystalline gold films of nano-thickness deformed by a spherical indenter using a recently developed freestanding membrane test. Freestanding membranes of gold were centrally deflected using a spherical indenter attached to a MEMS load cell. Fabrication of the films for these experiments yielded films 100 nm thick and 500 μm in diameter. We observed that the plastically deformed thin films recover completely in time at room temperature. One particular film was loaded 4 consecutive times, with the fourth loading leading to its fracture after full recovery from the three prior loadings. Observation of this phenomenon directed us to term this behavior “Ultra Low cycle fatigue”.