Uniform tensile elongation in Au-Si core-shell nanowires

J Godet and C Furgeaud and L Pizzagalli and MJ Demkowicz, EXTREME MECHANICS LETTERS, 8, 151-159 (2016).

DOI: 10.1016/j.eml.2016.03.023

In order to evaluate the role of a hard amorphous silicon (a-Si) shell on the deformation of a soft crystalline gold core, we investigated the mechanical properties of the Au@a-Si core-shell nanowire ( NW) by using molecular dynamics simulations. We first optimized an existing parametrization of the MEAM potential to better reproduce the mechanical properties of gold and silicon as well as Au-Si interactions. The comparison of the tensile tests performed on pristine Au NW, a-Si shell and Au@a-Si core-shell NW revealed that the hard amorphous shell works against the growth of the ledges left by localized plasticity. In consequence, the localized plasticity and the expansion of nano-twin are reduced. A homogeneous plastic deformation of the core-shell was then observed at almost a constant flow stress equal to the yield stress. This behavior is characteristic of an elastic-perfect plastic material. (C) 2016 Elsevier Ltd. All rights reserved.

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