Deformation Behavior of Nanoporous Metals

Biener, Juergen; Hamza, A. V.; Hodge, Andrea M.

doi:10.1007/978-0-387-78701-5_6

Cited by 15 publications

(14 citation statements)

References 65 publications

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“…As predicted by the Gibson-Ashby foam scaling equations [25], the porosity drastically reduces the stiffness relative to massive gold. Most experiments on np-Au find effective stiffness values considerably below the Gibson-Ashby prediction for the respective solid fraction [26,27], even though an enhanced stiffness has also been reported [28]. Recent modeling highlights the role of microstructural disorder in enhancing the effective compliance [29].…”

Section: Introductionmentioning

confidence: 99%

Electrical stiffness modulation—confirming the impact of surface excess elasticity on the mechanics of nanomaterials

Mameka¹,

Markmann

Jin

et al. 2014

Acta Materialia

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Local variations of the stiffness at surfaces may affect the elastic response of nanostructures, yet experiments disagree on magnitude and even sign of the surface excess elastic constants. The present study reports the variation in the effective macroscopic stiffness of bulk samples of nanoporous gold when the surface state is modulated under potential control in an electrochemical environment. Using in situ experiments in a dynamic mechanical analyzer to measure the storage and loss moduli, we show that adsorption of ≤ 1 atomic monolayer of oxygen species as well as a capacitively controlled excess of electrons at the surface stiffen the material while oxygen desorption/electron depletion enhance the compliance. Relative changes in the effective stiffness of up to 8% imply the variation of a surface excess elastic constant in the order of 60 N/m, much larger than the absolute value of that constant deduced from previous atomistic simulation studies of clean surfaces. Since the electrode potential affects exclusively the surface, our observations provide conclusive evidence for the impact of local stiffness variation at surfaces on the effective elastic response of nanostructures.

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Section: Introductionmentioning

confidence: 99%

Electrical stiffness modulation—confirming the impact of surface excess elasticity on the mechanics of nanomaterials

Mameka¹,

Markmann

Jin

et al. 2014

Acta Materialia

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“…Their excellent deformability under compression enables experiments that provide access to strain-rate sensitivity [10], elastic and plastic Poisson's ratios [13,16], as well as the evolution of flow stress and stiffness during the plastic densification of the network [12,14,17,18]. Of particular relevance is the observation of strong variations of strength as well as stiffness with ligament size [1,2,[6][7][8]10,11,14]. This finding connects experiments on NPG to topics of interest in the field of small-scale plasticity.…”

Section: Introductionmentioning

confidence: 64%

“…Several studies (see, e.g., Ref. [8] and the references therein) refer the elasticity of NPG to the Gibson-Ashby scaling relation for the stiffness of foams [33],…”

Section: Resultsmentioning

confidence: 99%

“…Nanoporous metals, and specifically nanoporous gold (NPG), made by dealloying are emerging as model systems for understanding the mechanical behavior of small-scale solids and of nanomaterials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The materials exhibit a uniform microstructure in the form of a network of nanoscale "ligaments", whose size can be adjusted to values between a few and several hundred nanometers [4].…”

Section: Introductionmentioning

confidence: 99%

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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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“…Example systems include micro-and nano-electro-mechanical devices and functional cellular solids with micro-and nano-sized morphological features, which promise tremendous technological and scientific potential. Nanoporous metals excel through unique physical, chemical, and mechanical characteristics (Biener et al, 2007), owing to the abundance of free surfaces. Depending on their degree of structural order, one distinguishes between nanoporous foams and structural materials (or, lattice materials).…”

Section: Introductionmentioning

confidence: 99%

Surface effects in nanoscale structures investigated by a fully-nonlocal energy-based quasicontinuum method

Amelang

Kochmann

2015

Mechanics of Materials

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a b s t r a c tSurface effects in nanoscale mechanical systems such as nanoporous solids or small-scale structures can have a significant impact on the effective material response which deviates from the material behavior of bulk solids. Understanding such phenomena requires modeling techniques that locally retain atomistic information while transitioning to the relevant macroscopic length scales. We recently introduced a fully-nonlocal energy based quasicontinuum (QC) method equipped with new summation rules. This technique accurately bridges across scales from atomistics to the continuum through a thermodynamicallyconsistent coarse-graining scheme. Beyond minimizing energy approximation errors and spurious force artifacts, the new method also qualifies to describe free surfaces, which is reported here. Surfaces present a major challenge to coarse-grained atomistics, which has oftentimes been circumvented by costly ad hoc extensions of the traditional QC method. We show that our new coarse-graining scheme successfully and automatically reduces spurious force artifacts near free surfaces. After discussing the computational model, we demonstrate its benefits in the presence of free surfaces by several nanomechanical examples including surface energy calculations, elastic size effects in nano-rods and in plates with nano-sized holes. Overall, we demonstrate the importance of surface effects as well as a new strategy to accurately capture those computationally via coarse-grained atomistics.

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Deformation Behavior of Nanoporous Metals

Cited by 15 publications

References 65 publications

Electrical stiffness modulation—confirming the impact of surface excess elasticity on the mechanics of nanomaterials

Electrical stiffness modulation—confirming the impact of surface excess elasticity on the mechanics of nanomaterials

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

Surface effects in nanoscale structures investigated by a fully-nonlocal energy-based quasicontinuum method

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