Comprehensive investigations of material properties in crystalline systems require information spanning atomistic to continuum scales. Mesoscale models play a crucial role in this context. They enable the study of large systems and long timescales while retaining microscopic details relevant to the targeted applications. This presentation illustrates recent results on key aspects of microstructure evolution in crystalline systems obtained via newly developed mesoscale frameworks for defects and interfaces. Using a bicrystallography-respecting continuum model that incorporates parameters obtained from atomistic methods, we first discuss phenomena associated with disconnection-mediated grain boundary (GB) motion, such as GB faceting and grain rotation. Then, through a phase-field formulation of this model, we demonstrate that internal stresses generated by disconnection flow (shear coupling) induce significant deviations from classical curvature-driven grain growth in microstructures. This provides a compelling explanation for the lack of correlation between GB velocity and curvature observed in recent experiments, identifying its primary cause. In the final section, an overview of other mesoscale frameworks that build upon the phase-field crystal model and its coarse-graining is provided. Representative results are presented, including the effects of temperature cycling on GB motion, as well as an emerging general framework for analyzing defect dynamics in systems with microscopic order, which extends beyond conventional crystals.
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