The influence of dislocation mobility on the evolution of dislocation microstructures during plastic deformation is studied via an atomistically-informed discrete dislocation dynamics (DDD) framework. First, the role of the dislocation character angle and non-Schmid stresses on the mobility of dislocations is studied using molecular dynamics (MD) simulations of straight dislocations and dislocation shear loops in Al. Empirical piecewise dislocation mobility functions, which account for linear phonon damping and non-linear radiative damping mechanisms are derived from MD simulations of straight dislocations. Then, the data describing the dislocation mobility laws are incorporated into the DDD framework. DDD simulations of isolated dislocation loop expansion show strong agreement with MD simulation results, validating the nonlinear multiscale implementation. For instance, nuances associated with loop expansion, such as modified mobility due to the local stress state and faceting due to modified core structure, as observed in MD, are captured by DDD simulations. Finally, large-scale DDD simulations are performed to elucidate the role of dislocation mobility functions on the deformation response of dislocation networks. The results demonstrate that the use of character angle and stress state dependent dislocation mobility laws, which account for changes in dynamics due to altered core structure, provides quantifiable changes to the plastic deformation path, ultimately leading to different final microstructures. This highlights the importance of using detailed descriptions of dislocation dynamics in mesoscale plasticity models.

Hierarchical Multiscale Study of the Role of Dislocation Mobility on Plasticity in Aluminum

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