MD simulations of strengthening by graphene in iron crystals

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In iron alloys, the increase in strength caused by solid solution, precipitate and grainboundary strengthening, plays an outstanding role in the technical application of the materials. In this project, the influence of nanoscale graphene discs embedded into the iron matrix and of carbon in solid solution on the mechanical properties, respectively, is investigated by means of ab initio and molecular dynamics (MD) simulations. The addition of graphene disks is expected to improve several mechanical properties. In particular, the thermal stability of the graphene discs and the properties of elasticity, strength and plasticity of the iron/graphene composite material are of importance. To estimate the thermal stability of the graphene discs, ab initio simulations are performed, which are also used to improve the interatomic potentials for the MD simulations. Molecular dynamics simulations using single- and polycrystals will be performed for different temperatures, carbon and graphene concentrations, as well as for different sizes, distances and orientations of the graphene discs.The objectives of the simulations are fundamental findings concerning dislocation/precipitate interactions, stress fields and residual stresses in the crystal lattice caused by the graphene discs or alloyed carbon atoms, and the associated changes in the mechanical properties of these materials.For the first time, MD simulations are used to investigate whether and to which extent the properties of iron can be improved by the addition of graphene discs in the desired direction of maximum strength with maximum elasticity and best possible plastic deformability (ductility and fracture strain) respectively.