Effect of Interfacial Bonding on Dislocation Strengthening in Graphene Nanosheet Reinforced Iron Composite: A Molecular Dynamics Study

It is uncertain that the interfacial bonding is whether a strong chemical bond or a weak van der-Waals one in graphene-metal composites. The effect of interfacial bonding features on dislocation strengthening are still obscure. Herein, we have investigated the mechanical response and dislocation behaviors of graphene/Fe composite using molecular dynamics simulations. Lennard–Jones and embedded-atom typed potential is employed to model a weak and strong interfacial bonding, respectively. We have considered anisotropy in three cases where a pair of graphene nanosheet (GN) were placed on three orthogonal ({110}, {111} and {112}) plane. When the dislocation is directly blocked by the GN, the yield stress of the strong-bonded composite is higher than that of the weak-bonded one. After the dislocation depins from the strong-bonded {112} GN, the Orowan loop is formed without surface step, in contrast to that in the weak-bonded one. For the {111} GN/Fe, the dislocation bypasses the GN pair in the strong-bonded composite, where double cross-slip and dislocation neutralization on the top {110} slip plane occur opposed to the middle {110} plane in the weak-bonded case.