EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

As long as the samples are large compared to the atomistic scale, the material behavior can be described as a continuum, especially in fatigue applications. The disolacation arrangements that form during the fatigue of face-centered cubic materials are well-known and typically have structural dimensions ranging from a few hundred nanometers to a few micrometers. So what happens when the sample thickness of a bending specimen is less than one micrometer? To answer this question, micro-cantilevers prepared in a focused ion beam were cyclically loaded in an atomic force microscope up to several million load cycles. The large stress gradients halves the effictive beam thickness. However, a classical Wöhler behavior was still observed. The dislocation networks formed no longer correspond to the fatigue structures known from macrosized samples. Moreover, the specimen thickness also determines the fatigue life for nanometer-sized specimens.