Weissmüller, JörgJörgWeissmüller10512915770000-0002-8958-4414Sohn, SeoyunSeoyunSohn2025-10-072025-10-072025Technische Universität Hamburg (2025)https://hdl.handle.net/11420/57613Studying the mechanical performance of nano- and microscale porous materials enhances our understanding of small-scale solids and improves materials design for functional applications. This study investigates the microstructure and mechanical behavior of millimeter-sized samples with a nanoscale random network structure, integrating metal hydrides to expand their functionality. Notably, metals such as Nb and Pd can form solid solutions with hydrogen across a broad concentration range at relatively low temperatures. Therefore, nanoporous (np) Nb and np Pd, representing body-centered cubic (BCC) and face-centered cubic (FCC) crystal structures respectively, are fabricated and studied, with np Au serving as a benchmark. In the first part of the thesis, the mechanical behavior of np material is investigated with a focus on the role of its microstructure size and topology. Results from macro-compression tests and X-ray nanotomography of np Nb confirm that coarsening degrades yield strength and that its Young’s modulus deviates from scaling laws developed for np Au, a widely-investigated model system produced via aqueous dealloying. The scaled genus, a measure of the network's connectivity, of np Nb is lower than that reported for np Au, and this reduced connectivity provides an obvious explanation for the low modulus. From these observations, a novel scaling law that explicitly involves the scaled genus is established. Furthermore, the comparison between np Au and np Nb implies that structural dispersion should be acknowledged as an additional structural descriptor to draw an analogy between liquid-metal dealloyed and electrochemically dealloyed materials. The second part of the thesis focuses on the interaction dynamics between np Pd and hydrogen. Compared to np Nb, np Pd demonstrates significantly higher hydrogen absorption efficiency. The study aims to understand the role of geometry on the hydrogen charging kinetics by tuning the ligament size of np Pd and to understand the limiting subprocess. Hydrogen ad/absorption and desorption kinetics are analyzed using electrochemical impedance spectroscopy and potential jump tests. The results suggest that the interfacial injection of hydrogen is the controlling factor of the sorption rate. This injection process is analyzed from a thermodynamic perspective, with the Pd-H miscibility gap taken into account. The Butler-Volmer equation is adapted to model the injection rate consistent with the equation of state for the composition-dependent chemical potential at equilibrium in an interacting solid solution. The model successfully predicts the characteristic charging time observed in the np Pd-H system. Overall, this thesis establishes a coupled relationship between mechanics, microstructure, and hydrogen absorption kinetics, providing insights into the optimization of structural design in np materials, thereby paving the way for their applications as integrated material systems.Diese Studie untersucht das Zusammenspiel von Mechanik, mikrostruktureller Geometrie und Wasserstoffwechselwirkung in nanoporösen (np) Materialien, mit Fokus auf np Nb und np Pd sowie np Au als Referenz. Ein Skalierungsgesetz für den elastischen Modul, das die topologische Konnektivität einbezieht, wird entwickelt. Weitergehende experimentelle Untersuchungen an np Nb zeigen, dass strukturelle Dispersion beim Vergleich verschiedener Entlegierungsmethoden berücksichtigt werden muss. Im zweiten Teil wird die Wasserstoff-Sorptionskinetik von np Pd analysiert. Im Ergebnis dominiert die Grenzflächeninjektion die Sorptionskinetik, was zur Formulierung eines neuen Gesetzes für die Reaktionsgeschwindigkeit führt.enhttps://creativecommons.org/licenses/by/4.0/NanoporousPalladiumNiobiumHydrogenMechanical behaviorTechnology::620: Engineering::620.1: Engineering Mechanics and Materials Science::620.11: Engineering MaterialsNatural Sciences and Mathematics::530: PhysicsDoctoral Thesishttps://doi.org/10.15480/882.1593010.15480/882.15930Klassen, ThomasThomasKlassenOther