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Item type:Publication, Access status: with files , Scaling behavior of Poisson's ratio in hierarchical nanoscale network materialsHierarchical nanoscale network materials have gained increasing interest over the last decade attributing to their enhanced functional and mechanical performance, combined with reduced density. However, investigations into their Poisson's ratio, a key fundamental mechanical property, remain lacking. In this work, monolithic hierarchical nanoporous gold with tunable structure size and solid volume fraction were prepared via a two-step electrochemical dealloying method. By using in-situ digital image correlation technique, we measured their elastic and plastic Poisson's ratios during macroscopic compression. The effects of solid fraction, upper level ligament size and strain were explored systematically. We found that both the elastic and plastic Poisson's ratios are independent of the upper level ligament size and compressive strain. Notably, we introduced a novel scaling law of elastic Poisson's ratio with solid fraction in hierarchical nanoscale network materials and verified it experimentally. This study addresses a knowledge gap in the mechanics of hierarchical nanoscale network materials, offering a comprehensive understanding of their structure–mechanical property relationships. This insight provides a foundation for the design of novel materials and the optimization of their functional and mechanical properties.Publicationtype: Journal Article42 23 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Effects of structural hierarchy and size on mechanical behavior of nanoporous goldNanoporous 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.Publicationtype: Journal Article30 35 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Scaling between elasticity and topological genus for random network nanomaterialsWe explore the hypothesis that the variation of the effective, macroscopic Young's modulus, Eeff, of a random network material with its scaled topological genus, g, and with the solid fraction, φ, can be decomposed into the product of g- and φ-dependent functions. Based on findings for nanoporous gold, supplemented by the Gibson–Ashby scaling law for Eeff, we argue that both functions are quadratic in bending-dominated structures. We present finite-element-modeling results for Eeff of coarsened microstructures, in which g and φ are decoupled. These results support the quadratic forms.Publicationtype: Journal Article26 81 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Role of slice thickness quantification in the 3D reconstruction of FIB tomography data of nanoporous materials(Elsevier, 2024-02); ; ; ; In focused ion beam (FIB) tomography, a combination of FIB with a scanning electron microscope (SEM) is used for collecting a series of planar images of the microstructure of nanoporous materials. These planar images serve as the basis for reconstructing the three-dimensional microstructure through segmentation algorithms. However, the assumption of a constant distance between consecutively imaged sections is generally invalid due to random variations in the FIB milling process. This variation complicates the accurate reconstruction of the three-dimensional microstructure. Using synthetic FIB tomography data, we present an algorithm that repositions slices according to their actual thickness and interpolates the results using machine learning-based methods. We applied our algorithm to real datasets, comparing two standard approaches of microstructure reconstruction: on-the-fly via image processing and ruler-based via sample structuring. Our findings indicate that the ruler-based method, combined with our novel slice repositioning and interpolation algorithm, exhibits superior performance in reconstructing the microstructure.Publicationtype: Journal ArticleScopus© Citations 2 63 125