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MM: Fachverband Metall- und Materialphysik

MM 44: Topical Session: Interface-dominated phenomena - Solutes at Interfaces II

MM 44.4: Vortrag

Mittwoch, 18. März 2020, 18:00–18:15, IFW A

Influence of impurities on the grain boundary strength in Ir — •Minaam Qamar, Matous Mrovec, and Ralf Drautz — Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, Germany

The present work aims to explore the role of segregated impurities on the grain boundary strength in iridium. Ab initio tensile tests were performed on both pure and impurity-segregated high angle symmetric tilt grain boundaries (GBs) and their cohesive strengths were compared. Two distinct GBs, Σ5(210)[001] and Σ11(113)[110], were chosen for the study with segregated H and Si atoms. The GBs show a contrasting behavior with respect to trapping sites of the impurity atoms: while the relatively loosely packed Σ5 GB has multiple low energy trapping sites, the close-packed Σ11 GB has very few. The behavior of the impurities is also markedly different: Si atoms show a much stronger segregation than H atoms. In addition, a detailed analysis of the migration of an H atom through the GBs found that the arrangement of atoms provides an easy migration path into the GB plane and a high energy barrier for reverse migration, effectively trapping the atom in the GB. However, despite the favorable segregation, neither H nor Si do not seem to significantly affect the cohesive properties of the GBs.