Nanoindentation study of size effects in nickel-graphene nanocomposites
SW Chang and AK Nair and MJ Buehler, PHILOSOPHICAL MAGAZINE LETTERS, 93, 196-203 (2013).
Metalgraphene nanocomposites find applications in nanoscale devices, as functional materials and can serve as a test bed to gain insight into fundamental deformation mechanisms of metals under geometric confinement. Here, we report full atomistic nanoindentation simulations for nickelgraphene nanocomposites with varied numbers of layers of graphene sheets to investigate the size effects on the hardness, and to understand how emerging dislocation loops interact with the nickelgraphene interface under varied geometric confinements. A detailed analysis of the plastic deformation mechanism shows that as dislocation loops reach the nickelgraphene interface, the local bending of the graphene sheet is altered and further dislocation propagation is blocked. An increase in the number of graphene layers decreases the hardness, but increases the maximum elastic deformation of the nickelgraphene nanocomposites. These findings indicate that the mechanical properties of nickelgraphene nanocomposites can be engineered by controlling the thickness of nickel and graphene layers, respectively.
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