Jeon, HansolHansolJeonMarkmann, JürgenJürgenMarkmannShi, ShanShanShi2024-05-302024-05-302024-07-01Acta Materialia 273: 119954 (2024-07-01)https://hdl.handle.net/11420/47649Nanoporous gold with a hierarchical structure has prospects as an advanced functional material with enhanced mechanical properties, but how the hierarchical structure affects its mechanical properties compared to a unimodal structure has not been revealed. Here, we investigate the mechanical behavior of hierarchically-structured nanoporous gold and unimodally-structured nanoporous gold with the same relative density by micropillar compressive tests in dry and electrolyte environment. The ligament size at the upper-level structure in hierarchically-structured nanoporous gold and the ligament size in unimodally-structured nanoporous gold are kept similar, while having hierarchically-structured samples with ligament sizes of 10 to 50 nm at lower-level structure. We find that hierarchically-structured nanoporous gold shows greater compressive strength and pronounced stress-variation by oxidization of the surface compared to unimodally-structured nanoporous gold. A ligament-size dependency on the lower-level structure in hierarchical samples is observed, with compressive strength and stress variation by surface oxidation increasing as the lower-level ligament size decreases. Three-dimensionally reconstructed structure analysis suggests that the enhanced mechanical properties of hierarchically-structured nanoporous gold are attributed to the better-connected network of ligaments originating from two separated dealloying-coarsening procedures. The influence of dislocation activities depending on characteristic sizes is also discussed to elucidate the distinguished mechanical behavior.en1359-64542024Elsevier Sciencehttps://creativecommons.org/licenses/by/4.0/Compressive testElectrochemically tunable strengthHierarchical structureMicrocompressionNanoporous goldSize effectTechnology::620: Engineering::620.1: Engineering Mechanics and Materials ScienceJournal Article10.15480/882.961410.1016/j.actamat.2024.11995410.15480/882.9614Journal Article