Regensburg 2019 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 5: Mechanical Properties
MM 5.9: Talk
Monday, April 1, 2019, 12:30–12:45, H46
Verifying Larché-Cahn theory by measuring open-system elasticity of nanoporous palladium(-gold)-hydrogen — •Shan Shi1,2, Jürgen Markmann1,2, and Jörg Weissmüller2,1 — 1Institut für Werkstoffforschung, Werkstoffmechanik, Helmholtz-Zentrum Geesthacht, Geesthacht — 2Institut für Werkstoffphysik und -technologie, Technische Universität Hamburg, Hamburg
Monolithic samples of nanoporous metals are suitable for studying the mechanical behavior of nanostructured metals via conventional, macroscale mechanical testing approaches. Here, we synthesized monolithic nanoporous palladium (np Pd) and palladium-gold (np Pd-Au) samples with ligament sizes below 10 nm, which allow fast hydrogen redistribution across their diameter when stress gradients are induced by bending. The corresponding variation of the Young's modulus during hydrogen absorption/desorption is measured by a dynamic mechanical analyzer. It is found that hydrogen sorption enables more than 30% reversible compliance variation in np Pd. Moreover, the redistribution of hydrogen, i.e. the change of local hydrogen concentration inside the ligaments, during the deformation causes an additional reduction of the effective elastic coefficients in the single-phase regime of Pd(-Au)-H at low hydrogen concentration. The measured Young's modulus shows excellent agreement with the prediction by the Larché-Cahn theory of open-system elasticity.