Computational Characterizations on the Grain-size-dependent Properties of Polycrystalline Nanomaterials

The microstructures of real nanomaterials can be quite complex with variety of grain sizes aligned in different crystal orientations and structural defects possibly created in a fabrication process. Material properties of these polycrystalline materials are generally known strongly dependent on the nanoscale morphology. First principle calculations based on the density functional theory need to be employed in these atomic characterizations; however, it may not be suitable for the polycrystalline nanomaterials for which large number of atoms is required in the simulation model. Instead, a mesoscale computer simulation scheme is employed to investigate these morphology-dependent mechanical properties of polycrystalline materials. We demonstrated the Voronoi construction of various polycrystalline atomic models such as two-dimensional graphene and three-dimensional silicon carbide. General behavior of the mechanical characteristics of the bulk nanostructured silicon carbide (SiC) was addressed, particularly the contribution of grain sizes. From this study, the optimal grain size was determined near 10 nm under tensile and compressive deformations.