Weakened Flexural Strength of Nanocrystalline Nanoporous Gold by Grain Refinement

Gwak, Eun‐Ji; Kim, Ju‐Young

doi:10.1021/acs.nanolett.6b00062

Cited by 46 publications

(19 citation statements)

References 48 publications

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“…Various aspects of the mechanical properties of NPG have been experimentally studied in bending [8,9], compression [10,11], tension [12,13], indentation [9,14] and non-contact ultrasonics [15]. Computational studies have used mechanics of materials approaches based on a -unit-cell‖ of the NPG structure [16][17][18], finite element methods (FEM) [16,19] and molecular dynamics (MD) [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties of nanoporous gold in tension

2017

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We report results of the tensile properties of nanoporous gold (NPG) as a function of the density and average ligament diameter. As-dealloyed tensile samples were thermally treated to coarsen the length scale of the NPG structure while increasing the sample density resulting from thickness reductions. The behaviors of samples with mean ligament diameters ranging from 30-750 nm and corresponding densities ranging from 0.30-0.57 that of bulk gold were examined. Digital image analysis was used to obtain ligament size histograms that were fit to the Weibull distribution. The Young's modulus was found to obey a power law, but with an exponent larger than that predicted by Gibson-Ashby scaling. The fracture behavior showed a brittle-ductile transition as a function of increasing ligament size. For samples characterized by a mean ligament diameter less than ~ 220 nm, the tensile behavior was linear elastic to sample fracture while samples with larger scale ligaments showed macroscopic yielding prior to fracture. These results are interpreted within the framework of extreme value statistics.

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Section: Introductionmentioning

confidence: 99%

Mechanical properties of nanoporous gold in tension

2017

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“…The hardness and elastic modulus of nanoporous silver with different ligament size are also determined at the same indentation depth of 1000 nm. Relationships of hardness and elastic modulus versus ligament size of nanoporous silver as well as nanoporous gold [10,[21][22][23][24][25] are plotted in Fig. 5 for comparison.…”

Section: Resultsmentioning

confidence: 99%

“…Biener's research [9] demonstrates that nanoindentation hardness and compressive strength of nanoporous gold depend strongly on ligament size in a way not described by the conventional Gibson–Ashby scaling model. Gwak [10] investigated the mechanical behaviours of nanoporous gold with different densities of initial dislocations and grain boundaries by nanoindentation and three‐point bending test. The results showed that high density of grain boundaries do not strengthen nanoporous gold.…”

Section: Introductionmentioning

confidence: 99%

Effect of nanoindentation depth and ligament size on mechanical properties of nanoporous silver

Lü

Wang

et al. 2018

Micro & Nano Letters

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Mechanical properties of nanoporous silver have been investigated by nanoindentation. Experiment shows that the hardness and elastic modulus are both involved with strong surface size effect. Under the same loading rate, hardness decreases from 56.7 to 26 MPa along with indentation depth increasing from 200 to 2000 nm, while the corresponding elastic modulus increases from 2.68 to 3.73 GPa. In the case of the same indentation depth, the hardness decreases from 53 to 7.4 MPa with ligament size increasing from 100 to 198 nm, and the corresponding elastic modulus reduces from 4.7 to 0.17 GPa. The calculated indentation size effect index m is 0.34, revealing that nanoporous silver has a good ductility in micro-state, but brittle in the macro-state.

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“…Machined precursor alloys were annealed at 800 °C for 24 hours to release residual stress introduced during mechanical polishing and machining. Samples were immersed in 35% nitric acid solution at 80 °C for 72 hours with stirring, producing np-Au with ligament size of 130 nm 37, 38 . Ligament sizes were measured by diameter of ligament necks, possibly thinnest part, from at least 100 measurements on SEM images.…”

Section: Methodsmentioning

confidence: 99%

Wall-thickness-dependent strength of nanotubular ZnO

Kang

Kim

Jeon

et al. 2017

Sci Rep

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We fabricate nanotubular ZnO with wall thickness of 45, 92, 123 nm using nanoporous gold (np-Au) with ligament diameter at necks of 1.43 μm as sacrificial template. Through micro-tensile and micro-compressive testing of nanotubular ZnO structures, we find that the exponent m in , where is the relative strength and is the relative density, for tension is 1.09 and for compression is 0.63. Both exponents are lower than the value of 1.5 in the Gibson-Ashby model that describes the relation between relative strength and relative density where the strength of constituent material is independent of external size, which indicates that strength of constituent ZnO increases as wall thickness decreases. We find, based on hole-nanoindentation and glazing incidence X-ray diffraction, that this wall-thickness-dependent strength of nanotubular ZnO is not caused by strengthening of constituent ZnO by size reduction at the nanoscale. Finite element analysis suggests that the wall-thickness-dependent strength of nanotubular ZnO originates from nanotubular structures formed on ligaments of np-Au.

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Weakened Flexural Strength of Nanocrystalline Nanoporous Gold by Grain Refinement

Cited by 46 publications

References 48 publications

Mechanical properties of nanoporous gold in tension

Mechanical properties of nanoporous gold in tension

Effect of nanoindentation depth and ligament size on mechanical properties of nanoporous silver

Wall-thickness-dependent strength of nanotubular ZnO

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