12 Strain-Rate Effects

Strain-rate effects are intrinsic to all materials deformations, in theory as well as modeling, experiments, or molecular simulations. When the deformation rate is significantly different from the rate of observation or analysis, it is unlikely that the underlying mechanisms governing the deformation at very different rates can be properly revealed or inferred. We investigate a feedback- localization phenomenon in the propagation of a single dislocation in a crystalline metal over a range of strain rates. The upturn behavior of the flow stress suggests a crossover from thermal activation to strain localization. By further considering the process of dislocation interaction with an intrinsic defect such as a self-interstitial atom cluster, one can construct a mechanism map in temperature and strain rate. Lastly, we comment on an analogy between crystal plasticity and glass rheology where strain rate plays a fundamental and structure-aware role.