Publisher DOI: 10.1016/j.actamat.2015.04.021
Title: Anomalous compliance and early yielding of nanoporous gold
Language: English
Authors: Ngo, Dinh Bao Nam  
Stukowski, Alexander 
Mameka, Nadiia 
Markmann, Jürgen 
Albe, Karsten 
Weissmüller, Jörg 
Keywords: Elasticity of nanomaterials; Molecular dynamics; Nanoporous; Small-scale plasticity; Physics - Materials Science; Physics - Materials Science
Issue Date: 21-May-2015
Publisher: Elsevier Science
Source: Acta Materialia 93 (2015) 144-155 (2015-05-21)
Abstract (english): 
We present a study of the elastic and plastic behavior of nanoporous gold in compression, focusing on molecular dynamics simulation and inspecting experimental data for verification. Both approaches agree on an anomalously high elastic compliance in the early stages of deformation, along with a quasi immediate onset of plastic yielding even at the smallest load. Already before the first loading, the material undergoes spontaneous plastic deformation under the action of the capillary forces, requiring no external load. Plastic deformation under compressive load is accompanied by dislocation storage and dislocation interaction, along with strong strain hardening. Dislocation-starvation scenarios are not supported by our results. The stiffness increases during deformation, but never approaches the prediction by the relevant Gibson-Ashby scaling law. Microstructural disorder affects the plastic deformation behavior and surface excess elasticity might modify elastic response, yet we relate the anomalous compliance and the immediate yield onset to an atomistic origin: the large surface-induced prestress induces elastic shear that brings some regions in the material close to the shear instability of the generalized stacking fault energy curve. These regions are elastically highly compliant and plastically weak.
ISSN: 1359-6454
Journal: Acta materialia 
Institute: Werkstoffphysik und -technologie M-22 
Document Type: Article
Project: SFB 986: Teilprojekt B2 - Feste und leichte Hybridwerkstoffe auf Basis nanoporöser Metalle 
More Funding information: Support by SFB 986 “Taylor-Made Multiscale Materials Systems – M3”, subproject B2.
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