Dislocation-obstacle interactions: dynamic experiments to continuum modeling

Incorporating the interaction of dislocations with obstacles remains a challenge in the development of predictive large-scale plasticity models. The need is particularly important in the elastic-plastic transition region where these interactions can dominate the behavior. By combining post-mortem analysis with dynamic straining in the transmission electron microscope, the atomic processes governing glissile dislocation reactions and interactions with obstacles has been determined. This information has been incorporated at least phenomenologically in models to assess the macroscopic stress-strain response. Two examples will be presented to demonstrate the methodology. The first example considers the interaction of dislocations with small vacancy Frank loops and the formation of defect-free channels in copper, and the second with the influence of imperfect annealing twin boundaries on the macroscopic stress-strain response in silver. In both examples, the importance of grain and twin boundaries as dislocation sources will be demonstrated