Berlin 2018 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 8: Topical session (Symposium EPS and MM): Mechanical Properties at Small Scales

MM 8.4: Vortrag

Montag, 12. März 2018, 12:45–13:00, TC 006

Effect of hard amorphous shell on gold nanowire during mechanical cycling — •Maxime Guillotte, Laurent Pizzagalli, and Julien Godet — Pprime Institute, CNRS, University of Poitiers - France

In order to evaluate the role of a hard amorphous silicon (a-Si) shell on the deformation of a soft crystalline gold core, we have investigated the mechanical properties under tensile and compressive cycling of the Au@a-Si core-shell nanowire (NW) by molecular dynamics simulations. We used an existing parametrization of the MEAM potential that has been optimized to better reproduce the mechanical properties of gold and silicon as well as the Au-Si interactions. The comparison of the mechanical tests performed on pristine Au NW and Au@a-Si core-shell NW reveals that the hard amorphous shell is able to confine the plasticity inside de core. In consequence, the localized plasticity and the expansion of nano-twin are reduced. The confinement of the dislocations in the core also leads to a homogeneous plastic deformation of the core-shell nanowire at almost constant flow stress equal to the yield stress up to a strain of 50%. This behavior is characteristic of an elastic/perfect-plastic mechanical regime. During the cycling tests, it also seems that the hard amorphous shell is is at the origin of the recovery of the FCC core.