Insight into Indentation Processes of Ni-Graphene Nanocomposites by Molecular Dynamics Simulation

Abstract

AbstractMolecular dynamics simulations provide insight into the processes underlying material plasticity and hard-ness. We demonstrate its uses here for the special case of a metal-matrix nanocomposite, viz. Ni-graphene. A series of increasingly more complex simulation scenarios is established, starting from a single-crystalline matrix over bi-crystal samples to fully polycrystalline arrangements. We find that the nanocomposite is weaker than the single-crystalline metal, since the graphene flakes are opaque to dislocation transmission and thus constrain the size of the dislocation network produced by the indenter. However, the flakes increase the hardness of a polycrystalline metal matrix. This is caused by dislocation pile-up in front of the flakes as well as dislocation absorption (annihilation) by the graphene flakes.