Interpreting anomalous low-strength and low-stiffness of nanoporous gold: Quantification of network connectivity

Liu, Lingzhi; Ye, Xing-Long; Jin, Hai-Jun

doi:10.1016/j.actamat.2016.07.033

Cited by 107 publications

(102 citation statements)

References 52 publications

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“…38 'Effective' relative densities of dealloyed materials were found to be only 1/4 of the real relative densities. 39 A similar concept may apply for the present case of electrical resistance, since conductive channels are only given by load Fig. 3 Increase of the electrical resistance R as a function of charge flow Q/Q tot recorded for nanoporous gold (black) and platinum (red) during dealloying (A) with the corresponding degree of dealloying a (B), and relative porous cross section area A p /A 0 (C) according to eqn (7) and (8).…”

Section: 35mentioning

confidence: 99%

“…Such an incompatibility with the Gibson-Ashby model has been reported previously for the mechanical properties of dealloyed materials. 38,39 Besides a general weakness of the Gibson-Ashby model for describing porous structures with relatively high j*/j s values due to overcounting of ligaments, also the special topology of dealloyed metals has to be taken into account: while the description by Gibson and Ashby is based on a perfectly connected polyhedral foam as model-structure, nanoporous metals prepared by dealloying contain a large fraction of broken or dangling ligaments. These unconnected network branches do not contribute to the macroscopic strength of the material as 'load bearing ligaments'.…”

Section: 35mentioning

confidence: 99%

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Dealloying progress during nanoporous structure evolution analyzed by in situ resistometry

Steyskal

Seidl

Graf

et al. 2017

Phys. Chem. Chem. Phys.

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The progress of dealloying, an electrochemical synthesis method capable of producing nanoporous structures with bulk outer dimensions, is studied by in situ resistometry. The resistance increases by three orders of magnitude while nanoporous gold or platinum is formed. Simultaneous monitoring of charge flow and electrical resistance increase proves to be an ideal combination for analyzing the etching progress, which in accordance with recent studies can be demonstrated to occur in two steps referred to as 'primary (or bulk) dealloying' and 'secondary (or ligament) dealloying'. A model is developed, which describes the resistance increase during etching as governed by the reduction of the master alloy backbone in favor of the nanoporous structure. This new approach allows an evaluation of the etching front propagation (primary dealloying) as well as the status of the already porous structure (secondary dealloying).

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Section: 35mentioning

confidence: 99%

Section: 35mentioning

confidence: 99%

Dealloying progress during nanoporous structure evolution analyzed by in situ resistometry

Steyskal

Seidl

Graf

et al. 2017

Phys. Chem. Chem. Phys.

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“…Besides very fundamental calculations such as density functional theory (DFT) [13] and molecular dynamics simulations (MD) [11,12,14], there are several simplified finite element method (FEM) models [6,[13][14][15][16][17][18] and even analytical models [19][20][21][22][23][24] for predicting mechanical properties. In many modeling approaches the complex NPG Before the skeleton data were translated into the skeleton FEM beam model, the geometrical data were thoroughly analyzed.…”

Section: Introductionmentioning

confidence: 99%

Skeletonization, Geometrical Analysis, and Finite Element Modeling of Nanoporous Gold Based on 3D Tomography Data

Richert

Huber

2018

Metals

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Abstract:Various modeling approaches simplify and parametrize the complex network structure of nanoporous gold (NPG) for studying the structure-property relationship based on artificially generated structures. This paper presents a computational efficient and versatile finite element method (FEM) beam model that is based on skeletonization and diameter information derived from the original 3D focused ion beam-scanning electron microscope (FIB-SEM) tomography data of NPG. The geometrical skeleton network is thoroughly examined for a better understanding of the NPG structure. A skeleton FEM beam model is derived that can predict the macroscopic mechanical behavior of the material. Comparisons between the mechanical response of this skeleton beam model and a solid FEM model are conducted. Results showed that the biggest-sphere diameter algorithm implemented in the open-source software FIJI, commonly used for geometrical analysis of microstructural data, overestimates the diameter of the curved NPG ligaments. The larger diameters lead to a significant overestimation of macroscopic stiffness and strength by the skeleton FEM beam model. For a parabolic shaped ligament with only 20% variation in its diameter, a factor of more than two was found in stiffness. It is concluded that improved algorithms for image processing are needed that provide accurate diameter information along the ligament axis.

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“…3 are from an interval of compression in which the density increases by a factor of 1.35, from φ = 0.308 to φ = 0.415, while the stiffness increases more than 5-fold, from Y eff = 380 MPa to Y eff = 1.96 GPa. Other microstructural changes, for example changes in the network topology [14,19,20,35], might also contribute to the increase of the elastic modulus.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, Huber et al [12] and Roschning et al [17] have shown that disorder in the array of connecting nodes substantially reduces the stiffness. A less-than-ideal connectivity of the network -for instance in the form of "broken ligaments" -would act similarly [14,15,19,20].…”

Section: Introductionmentioning

confidence: 99%

On the origin of the anomalous compliance of dealloying-derived nanoporous gold

et al. 2017

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The origin of the anomalously compliant behavior of nanoporous gold is studied by comparing the elasticity obtained from molecular dynamics (MD) and finite element method (FEM) simulations. Both models yield a compliance, which is much higher than the predictions of the Gibson-Ashby scaling relation for metal foams and thus confirm the influence of other microstructural features besides the porosity. The linear elastic FEM simulation also yields a substantially stiffer response than the MD simulation, which reveals that nonlinear elastic behavior contributes decisively to the anomalous compliance of nanoporous gold at small structure size. Bibliographic details

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Interpreting anomalous low-strength and low-stiffness of nanoporous gold: Quantification of network connectivity

Cited by 107 publications

References 52 publications

Dealloying progress during nanoporous structure evolution analyzed by in situ resistometry

Dealloying progress during nanoporous structure evolution analyzed by in situ resistometry

Skeletonization, Geometrical Analysis, and Finite Element Modeling of Nanoporous Gold Based on 3D Tomography Data

On the origin of the anomalous compliance of dealloying-derived nanoporous gold

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