Nanoporous Au: Statistical analysis of morphological features and evaluation of their influence on the elastic deformation behavior by phenomenological modeling

This work investigates the relationship between the morphology of nanoporous (NP) Au metal foams and their response to elastic deformation. A detailed statistical analysis of scanning electron micrographs has been performed to obtain a quantitative description of ligaments and nodes in terms of characteristic lengths. The thickness of ligaments is shown to vary along their length according to a quadratic function. The relatively broad distribution of ligament length and thickness indicates that local structures can be significantly different from each other. Invariably, nodes are quite massive. Based on this experimental evidence, a phenomenological model of the NP Au structure has been developed to describe its mechanical response within the elastic deformation range. The elementary structural unit consists of a cubic node connecting with six half ligaments with a square cross-section and a parabolic thickness profile. The model predicts that the bending behavior is restricted to the central portion of the ligaments, the effective response being modulated by the ligament characteristic lengths. Model predictions are found to agree fairly well with experimental data.