Atomistic simulations of the mechanical properties of nanocrystalline copper at room temperature

Abstract

Molecular dynamics simulations are performed to study the mechanical behavior of high-angle and low-angle nanocrystalline copper with an average grain size in the range of 3.7-6.7nm and the porous nanocrystalline copper with an average grain size of 5.8 nm at room temperature. It is found that the grain boundary sliding is the main deformation mechanism in the high-angle samples while both dislocation motion and grain boundary activities play an important role in the plastic deformation for low-angle samples. The grain boundary activities in the low-angle samples are manifested by migration, breakup and dislocation gliding within grain boundaries. The orientation of the grains to the tensile direction strongly affects the mechanical behavior of the low-angle samples. For the porous sample, the cracklike voids do not propagate along grain boundaries. Voids assist the formation of shear planes in some situations.