Regensburg 2025 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 11: Topical Session: Defects of Defects
MM 11.5: Vortrag
Dienstag, 18. März 2025, 12:00–12:15, H10
Defect Phase Diagrams for Grain Boundaries in Mg: Chemical trends at Finite Temperatures — •Prince Mathews1, Rebecca Janisch2, Tilmann Hickel1,3, and Jörg Neugebauer1 — 1Max-Planck-Institut für Nachhaltige Materialien GmbH, Düsseldorf — 2Interdisciplinary Centre for Advanced Materials Simulation, Ruhr Universität Bochum — 3Federal Institute for Materials Research and Testing (BAM), Berlin
Lattice defects are known to directly influence the behaviour of materials. The framework of defect phase diagrams (DPDs) offers a powerful and knowledge-based approach for the tailored design of materials by controlling defect phases in competition to bulk phases. Using ab-initio methods and automized workflows, the DPD for the example of Ga segregation to Σ7 [0001] 21.78∘ (sym. plane 12-30) Mg grain boundary is calculated. It predicts a series of defect phase transformations, which turn out to be in good agreement with transmission electron microscopy experiments. Similar to bulk phases, the stabilities of defect phases can change with temperature. Therefore, different approaches to extend the DPD considering the relevant entropy contributions are discussed. A new sub-lattice model, which is focused on the statistics of grain boundary site column coverages, provides promising insights into temperature-dependent processes of defect phase transformations.
Keywords: Magnesium; Grain Boundaries; Defect Phase Diagrams; Finite Temperature; Chemical Trends