Structural evolution of copper-silver bimetallic nanowires with core-shell structure revealed by molecular dynamics simulations

摘要

The molecular dynamics simulation method is used to investigate the tensile deformation mechanism of Cu-Ag core-shell nanowires. The results for the actual structure of the Cu-Ag core-shell nanowires after energy minimization processes indicate that the atoms in shell Ag are reconstructed when the shell thicknesses smaller than 1.0 nm, while the shell thickness increases from 1.0 nm to 1.5 nm, the shape of NWs change into irregular circle. And then the tension strain is performed along the [001] direction under the conditions of varying the shell thickness and the temperature, respectively. It is found that, in low temperature region, <500 K, with decreasing the shell thickness from 1.5 nm to 0.25 nm, the plastic deformation mechanism transforms from the misfit dislocation tube mechanism into the surface dislocation nucleation mechanism. When the temperature increases to the high region, >= 500 K, the plastic deformation mechanism then changes into the high temperature influence dislocation nucleation mechanism. A shell thickness-temperature plastic deformation map is proposed to reveal the transition among the three different plastic deformation mechanisms for Cu-Ag core-shell nanowires. (C) 2017 Elsevier B.V. All rights reserved.