Molecular Dynamics Study of Grain Size and Strain Rate Dependent Tensile Properties of Nanocrystalline Copper

Molecular dynamics simulations are performed to study the tensile properties of bulk nanocrystalline copper with different grain sizes at various loading rates. The simulation results prove that the tensile modulus decreases with decreasing grain size, and increases with increasing strain rate. The flow stress decreases with decreasing grain size, which is consistent with Inverse Hall-Petch relation. The Hall-Petch slope constant is found to be sensitive to strain rate. The grain size effect on the strain rate sensitivity has also been concerned. Then the deformation mechanisms of nanocrystalline copper under tension are examined with an emphasis on the contributions of grain boundaries.