MICROSTRUCTURAL EFFECTS ON THE CYCLIC RESPONSE OF FCC METALLIC ALLOYS - A DISLOCATION DYNAMICS STUDY

摘要

Three-dimensional dislocation dynamics (3D-DD) method is used to simulate the cyclic behavior of face-centered cubic (FCC) metallic alloys. The fatigue properties of these alloys are very much sensitive to their dislocation microstructures and dislocation interactions with grain boundaries and particles. The emphasis is to understand microscale mechanisms of dislocation evolution in such alloy systems. In this study, cyclic behavior of FCC metallic alloys containing impenetrable grain boundaries, hard coherent as well as shearable misfitting particles will be analyzed respectively. Plastic deformation is modeled through the motion of dislocations. The dislocation nucleation, dislocation interaction with obstacles and dislocation annihilation are incorporated in the model through a set of constitutive rules. The microstructure evolutions comprising of these mechanisms and stress-strain curves are obtained directly from simulation results. This technique is shown to be capable to predict cyclic deformation from a set of microstructures.