Predicting Slip Transfer from Atomistic to Microscale—Methodology, Mechanisms and Applications

Engineering alloys are usually heterogeneous and contain a high density of interfaces such as stacking faults, grain boundaries (GBs), and phase boundaries (PBs). When subjected to plastic deformation, the overall performance of these materials is largely dictated by the interaction between the dislocation-mediated slip and those interfaces. Due to the length-scale limitation, a fully atomistic model usually can only accommodate a few dislocations without considering much material microstructure complexities. In contrast, our concurrent atomistic-continuum (CAC) approach unifies the atomistic and continuum description of materials. It can accommodate the long-range dislocation slip and the atomically structured interfaces all within one model. Here we will present our recent development of an adaptive CAC for predicting slip transfer in plastically deformed polycrystalline alloys with its grain size spanning from nanometers to micrometers. The slip-interface reaction-induced complex internal stress as well as its contributions to the subsequent structure changes, such as lattice rotation, twinning (nucleation, growth, variant selection), and phase transformation, will be all characterized from the bottom up. The obtained results will be then informed into a local stress- or couple stress-based slip transfer metrics. An implementation of such metrics in higher length scale models, such as crystal plasticity finite element, dislocation dynamics, or phase field models, will significantly improve their predictive capability. This in turn, will lead to an atomistic-to-macroscale computational platform that can be used for predicting the microstructure evolutions in a variety of engineering materials exposed to extreme stress, corrosive, irradiations, and even a combination of them.