Effect of graphene network reinforcement and interface orientation on the mechanical behavior of nickel composites: A molecular dynamics study

This study investigates the effect of graphene network configuration and interface orientation on the mechanical behavior of graphene-reinforced nickel (Gr/Ni) composites under tensile and compressive loadings, using molecular dynamics simulations. Two graphene configurations, a single sheet ($\text{NiGr}[-]$, 0.66 vol%) embedded within the Ni matrix and a cross-shaped network ($\text{NiGr}[\times ]$, 1.0 vol%), were assessed across three interface orientations: Gr/Ni(100), Gr/Ni(110), and Gr/Ni(111). The obtained results show that graphene reinforcement significantly enhances the composites' strength, stiffness, and ductility across all crystallographic orientations. Notably, Gr/Ni composites exhibit superior tensile strength and Young's modulus, especially in the Gr/Ni(110) and Gr/Ni(111) orientations, with the $\text{NiGr}[\times ]$ configuration showing the highest performance. Under compression, the composites demonstrate remarkable increases in compressive strength, with the $\text{NiGr}[\times ]$ configuration again outperforming others. Dislocation density analysis reveals that while graphene effectively hinders dislocation motion under tension, its impact is reduced under compression due to sheet buckling and rippling. Additionally, the study highlights significant ductility enhancements in Gr/Ni composites, especially in the Gr/Ni(111) orientation, where the $\text{NiGr}[\times ]$ configuration sustains over five times the strain of pure Ni before failure. These findings underscore the potential of optimizing Gr/Ni composites for applications requiring exceptional mechanical performance and provide valuable insights for advanced material design.