Elucidating asymmetric yield behavior of copper nano-wires during tensile and compressive load

Abstract

Thermal and mechanical response of [0001]-oriented GaN nanowires during tensile loading and unloading J. Appl. Phys. 112, 083522 (2012); 10.1063/1.4759282 Symmetry-adapted non-equilibrium molecular dynamics of chiral carbon nanotubes under tensile loading The interface and surface effects of the bicrystal nanowires on their mechanical behaviors under uniaxial stretching J. Appl. Phys. 108, 074311 (2010); 10.1063/1.3477323Shape effects on the yield stress and deformation of silicon nanowires: A molecular dynamics simulation Molecular dynamic simulations were performed to investigate the effects of tensile and compressive loading on the mechanical properties of face-centered cubic single-crystal copper [001] nano-wires with diameters ranging from 2 to 10 nm. Characterization of the initial optimized structures revealed large variations in interatomic spacing, stress, and potential energy in all nano-wires, which resulted in tensile stress for surface atoms and compressive stress for internal atoms. This phenomenon is more apparent in thin nano-wires (<6 nm) than thick nano-wires (!10 nm). These variations are the origins of asymmetric yielding and asymmetric Poisson ratio in [001] copper nano-wires during tension and compression. For example, the Poisson's ratio exceeds 0.5 as the compressive strain approaches yield, indicating that the mechanical properties of single-crystal [001] nano-wire show strong directionality. The finding provides a fundamental understanding of the influence of the wire diameter on the mechanical properties of [001] nano-wires. V C 2013 AIP Publishing LLC.