Dresden 2026 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 34: Hydrogen in Materials I
MM 34.4: Vortrag
Donnerstag, 12. März 2026, 16:30–16:45, SCH/A215
Atomistically Informed Grain-Boundary Thermodynamics for Phase-Field Modelling of Hydrogen-Driven Microstructural Evolution in Aluminium — •Bharathi Ganesh Ganesan Sekar1, Ali Tehranchi1, Tilmann Hickel1, and Nils Warnken2 — 1Bundesanstalt für Materialforschung und -prüfung, Berlin, Germany — 2University of Birmingham, Birmingham, United Kingdom
Hydrogen-driven microstructural evolution in polycrystalline aluminium (Al) is strongly influenced by grain-boundary (GB) structure and hydrogen (H) segregation. We aim to develop an atomistically informed phase-field framework to describe these effects, with relevance to hydride formation. Molecular-statics simulations were performed for representative FCC Al symmetric-tilt boundaries Σ5(310), Σ5(210), and Σ3(111) to assess whether H segregation can initiate hydride formation. Instead, H induces defect-mediated structural transitions and shows distinct relaxation pathways during ingress and discharge. At high H content, the GB cleaves and free surfaces form. To generalise these insights, a library of 250 microstates was generated for each GB plane normal within the Σ5 family by sampling rigid-body translations and boundary-plane atomic fractions. This enables construction of GB energies as a function of plane normal, with temperature dependence introduced through Boltzmann weighting. H effects are included by evaluating segregation energies for the minimum-energy microstate of each plane normal, yielding H-chemical-potential-dependent GB energies. These results provide essential GB energetics for phase-field modelling of H-driven microstructural evolution in Al.
Keywords: Grain boundary energetics; Hydrogen segregation,; Hydride formation; Grain Boundary structural transitions; Hydrogen–grain boundary interaction