Regensburg 2025 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 4: Materials for the Storage and Conversion of Energy
MM 4.5: Talk
Monday, March 17, 2025, 11:15–11:30, H22
Hydride formation in open thin film metal hydrogen systems: Cahn-Hilliard-type phase-field simulations coupled to elasto-plastic deformations — •Stefan Wagner1, Alexander Dyck2, Johannes Gisy2, Frederik Hille2, Astrid Pundt1, and Thomas Böhlke2 — 1Institute for Applied Materials (IAM-WK), Karlsruhe Institute of Technology (KIT), Germany — 2Institute of Engineering Mechanics (ITM), Karlsruhe Institute of Technology, Germany
Metal-hydrogen systems are versatile model systems to study alloy thermodynamics and structural phase transitions. Hydrogen absorption and hydride formation in metals induce a volume expansion of the metal, leading to incompatibility stresses at internal and external interfaces. Resulting changes of the thermodynamic stability of phases in response to the mechanical constraint conditions can be understood by investigating the chemo-mechanical coupling [1,2]. Utilizing niobium-hydrogen thin films, combining a Cahn-Hilliard type phase-field theory and Finite-Element-Modeling (FEM) we study the feedback-loop of the local stress state, elasto-plastic deformations and hydrogen diffusion, determining the driving force of precipitation and growth of the hydride phase under open-system conditions. The simulation results are informed by and compared to measurements of the concentration-dependent stress state, chemical potential and phase separation in epitaxial niobium-hydrogen thin films adhered to sapphire substrates [3]. [1] A. Dyck, T. Böhlke, A. Pundt, S. Wagner, Scr. Mat. 247 (2024) 116117. [2] A. Dyck et al., Scr. Mat. 251 (2024) 116209. [3] A. Dyck et al., accepted to Mech. of Mat.
Keywords: Thin films; Thermodynamics; Hydride Formation; Coherency; Phase Field Modeling