Understanding the Low Cycle Fatigue Behavior of Single Crystal Cu at the Nano-scale: A Molecular Dynamics Study

Understanding the mechanical behavior of the key elements in alloys, at the nano scale leads to the design of optimum microstructure against fatigue failure. In the present study, low cycle fatigue simulations have been carried out on defect free single crystal Cu (face centered cubic) nano wire of size about 7.23 × 7.23 × 14.46 nm (aspect ratio of 2:1) at temperature 10 K by using molecular dynamics simulations. Yielding was found to be initiated from corners of the nano wire by forming stacking faults. It was observed that cyclic stress response of the model system depended on microstructure which was at the starting of reverse loading. Potential energy was used as a tool to investigate the fatigue deformation characteristics of the Cu nano wire. It was observed that the competition between hexagonal close packed atoms and disordered atoms [especially point defects, surface atoms and non-crystalline atoms (other than surface atoms)] governed the cyclic characteristics of the model system.