Collaborative Research: Novel Atomistic-Continuum Simulation of Sequential Grain Boundary-Dislocation Slip Transfer Reactions

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The research objective of this award is to advance a coupled atomistic-continuum simulation method to explore slip transfer at grain boundaries. Lack of such a method is a current obstacle to progress towards developing constitutive relations that reflect the structure and behavior of grain boundaries, for example in polycrystal plasticity. The problem is complicated by the need to account for long range interactions of dislocation fields while also considering the atomic-level structural detail of the interface. This research will explore processes of sequential dislocation reactions with bicrystal interfaces by maintaining full atomistic resolution of the interface reactions and successively coarse graining the field description away from the interfaces at distances that are normally inaccessible to fully resolved molecular dynamics. Such a capability will enable parametric studies of dislocation-grain boundary slip transfer reactions over the full range of grain boundary degrees of freedom, including tilt and twist boundaries, as well as asymmetric boundaries that often have faceted structure and can give rise to profuse dislocation nucleation. Nanotwinned structures with a wide range of twin spacing will also be considered. This work will use state-of-the-art embedded atom method potentials which have proven quite accurate for fcc metals such as Cu in modeling various aspects of dislocation nucleation, formation of stacking faults, and dislocation interactions This research will advance a computational method that couples fully atomistic descriptions of nanoscale metallic behavior to mesoscale and macroscale constitutive behavior. It will permit study of the complex interactions that occur between dislocations and grain boundaries in polycrystalline metals which will lead to physics-based predictive constitutive models for metals. This research will advance the multiscale modeling of metals and lead to improved simulation and ultimately design of materials. Results of the research will be incorporated into graduate courses at both institutions.