▎ 摘　　要

Graphene can be utilized as reinforcing interlayers in metal-matrix composites to improve their mechanical properties. This improvement is due to the ability of the graphene layers to transfer their exceptional strength to the metallic matrix, and their ability to hinder the propagation of dislocations inside the metallic systems. In these composites, the structure of the graphene layer (or nanoparticles) in the matrix and the interaction between graphene and metallic atoms play a vital role in the improvement of metal-graphene composites' mechanical properties. While the interaction between metal and graphene interface, when the graphene is on the top of a metallic layer, has been extensively studied, details of the interaction when the graphene is embedded inside a metal matrix are still highly unexplored. In this paper, we considered the structure of graphene and the interaction between graphene nanoparticle edges and nickel atoms when the graphene is embedded in the nickel matrix. Using ab-initio calculations, we found that when the graphene is embedded inside a nickel matrix, the most stable graphene structure is topfcc (with graphene nano-sheets being parallel to Ni(111) surface), which is a different configuration compared to the case of having graphene on the surface of a nickel slab. Also, we found that armchair edge energy is 0.8022(eV/angstrom) and zigzag edge energy is 2.5048(eV/angstrom) which implies armchair edge is more stable and creates less distortion inside the nickel matrix. Less distortion by armchair edge implies that nucleation of dislocation in composites will start later at armchair edges in comparison to zigzag edges during mechanical loading.