Mechanical properties of nanoscale copper under shear

Abstract

We study the effects of shear strain and stress in several nanoscale copper systems consisting of about 200,000 atoms with the effective-medium theory and molecular dynamics method. Both single and polycrystal systems are studied. In single crystals, we concentrate on dislocation initiation and propagation and briefly discuss, what happens under oscillatory loading. In case of polycrystals, we study the validity of the Hall–Petch relation under shear. The results indicate that both sub- and super-sonic dislocations may be present in copper. The minimum stress and strain, at which a dislocation initiated in a single crystal was 1.2 GPa and 4.6%. These values can be much larger than the values for a real copper sample, since polycrystalline microstructure was seen to decrease the system strength.