Graphene growth via chemical vapour deposition on cross-rolled surface-textured nickel-copper foils

The current work correlates the microstructure of multi-step cross-rolled (MSCR) and annealed polycrystalline nickel/copper (Ni/Cu) alloys with graphene synthesis using chemical vapor deposition (CVD). Due to the effects of higher shear stress and friction at the surface, multi-step cross-rolling induces significantly different textures at the surface and mid-thickness region, respectively. The transition of orientations through lattice curvature was analyzed using electron back-scattered diffraction (EBSD) technique. The lower stacking fault energy (SFE) of Ni/Cu alloys with a higher copper (Cu) content restricts the grain growth in annealed foils through the activation of a higher percentage of low-energy twin boundaries. Although annealing pure Ni samples resulted in multiple twinning variants, the 60/40:Ni/Cu alloy evolved with the highest number of twins per unit area. The essential deformation and recrystallization processes were elucidated via the alterations in strain hardening, extended recovery, and continuous recrystallization effects. The magnitudes of the Cu content are correlated with the number of layers of graphene. The results of the present study will motivate future work on different polycrystalline Ni/Cu alloys, with dissimilar surface textures, for controlling the quality of graphene, as characterized by Raman spectroscopy techniques.