Regensburg 2025 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 11: Topical Session: Defects of Defects

MM 11.4: Topical Talk

Tuesday, March 18, 2025, 11:30–12:00, H10

Grain Boundary Spinodals: Faceting Instability and the Role of Junction Energetics — •Fadi Abdeljawad — Lehigh University, Bethlehem, PA, USA 18015

Interfaces greatly influence the physical properties and stability of materials microstructures. Of particular interest in crystalline solids are phenomena that occur due to anisotropic interfacial properties. In polycrystalline aggregates, several experimental observations revealed that an initially flat GB profile may facet into hill-and-valley morphologies with well-defined planes and junctions connecting them. Dislocation-like defects exist at facet junctions, which in general connect GB facets with different atomic structures and interfacial properties. Based on classical atomistic simulations and mesoscale modeling, we examine GB faceting transitions and subsequent facet coarsening dynamics. Our modeling framework accounts for anisotropic interfacial energies, and it incorporates junction energetics and their non-local interactions. The hallmark of our approach is the ability to independently examine the various factors affecting this interfacial instability. Theoretical and computational studies predict the dominant growth morphologies as a function of GB facet junction energies. Furthermore, atomistic and mesoscale simulations show that when accounting for junction energetics GB faceting and subsequent facet coarsening is akin to spinodal decomposition in bulk materials. In broad terms, our work provides an avenue to account for GB structural transitions in models of microstructural evolution.

Keywords: grain boundary; faceting; atomistic simulations; phase transformations; interfaces