Molecular Dynamics Simulations Study on the Grain Size Dependence of Deformation and Failure Behavior of Polycrystalline Cu

摘要

The tensile deformation and failure behavior of polycrystalline Cu nanowires have been examined using molecular dynamics (MD) simulations at 10 K. MD simulations have been performed on polycrystalline Cu nanowires with grain size ranging from 1.54 to 5.42 nm. The simulation results indicate that the yielding as well plastic deformation in all the Cu nanowires proceeds by the slip of Shockley partial dislocations irrespective of grain size. Interestingly, the formation of fivefold twin and deformation induced grain growth has been observed during the plastic deformation. The polycrystalline Cu with the grain size of 5.42 nm fails through shear along the grain boundary (intergranular failure), while the shear along the slip planes within the grain (intra-granular failure) has been observed for grain size less than 5.42 nm. The variations of yield strength and flow stress at 10% strain as a function of grain size follows inverse Hall-Petch relation.