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MM: Fachverband Metall- und Materialphysik

MM 29: Poster II

MM 29.37: Poster

Tuesday, March 19, 2024, 17:00–19:00, Poster B

Phase transformation in the Palladium Hydrogen system: Effects of boundary conditions and stress relaxation on phase stabilities — •Stefan Wagner¹, Alexander Dyck², Astrid Pundt¹, and Thomas Böhlke² — ¹Karlsruhe Institute of Technology, Institute for Applied Materials - Materials Science and Engineering (IAM-WK), Karlsruhe, Germany — ²Karlsruhe Institute of Technology, Institute of Engineering Mechanics (ITM), Karlsruhe, Germany

The thermodynamic stability of phases in alloys undergoing structural phase transitions can be modified by constraints. Utilizing palladium-hydrogen as a model, within a linear-elastic chemo-mechanical approach we study modifications of the system's Helmholtz free energy and chemical potential upon different constraints. The palladium-hydrogen system decomposes into a solid solution phase and a hydride phase at critical conditions. Depending on the chosen elastic boundary conditions systematic variations of the driving force for hydride formation in temperature-concentration space are revealed.

In real systems plastic deformation can occur, when critical energy densities of the alloy are reached upon elastic straining. Plastic deformation is shown to strongly reduce the stability of the palladium-hydrogen solid solution phase on the expense of eased hydride formation.

Keywords: Metal; Hydrogen; Stress; Phase Transformation; Thermodynamics