Graphene has proved its significant role as a reinforcement material in improving the strength of polymers as well as metal matrix composites due to its excellent mechanical properties. In addition, graphene is also shown to block dislocation motion in a nanolayered metal-graphene composites resulting in ultra high strength. In the present paper, we demonstrate the synthesis of very hard Cu-Graphene composite foils by a simple, scalable and economical pulse reverse electrodeposition method with a well designed pulse profile. Optimization of pulse parameters and current density resulted in composite foils with well dispersed graphene, exhibiting a high hardness of ~2.5 GPa and an increased elastic modulus of ~137 GPa while exhibiting an electrical conductivity comparable to that of pure Cu. The pulse parameters are designed in such a way to have finer grain size of Cu matrix as well as uniform dispersion of graphene throughout the matrix, contributing to high hardness and modulus. Annealing of these nanocomposite foils at 300°C, neither causes grain growth of the Cu matrix nor deteriorates the mechanical properties, indicating the role of graphene as an excellent reinforcement material as well as a grain growth inhibitor.

The texture evolution in copper foils prepared by a rapid pulse reverse electrodeposition (PRED) technique using an 'additive-free' electrolyte and the subsequent correlation with the mechanical and electrical properties is investigated in the present study. Control over (111), (100) and (101) crystallographic textures in copper foils has been achieved by optimization of the pulse parameters and current density. Hardness as high as 2.0-2.7 GPa, while maintaining the electrical conductivity in the same range as that of bulk copper was exhibited by these foils. The complete study of controlling the (111), (100) and (101) textures, CSL Σ3 coherent twin boundaries, grain refinement and their effect on the mechanical and electrical properties is performed in detail by characterizing the foils with electron backscatter diffraction (EBSD), X-ray diffraction (XRD), nanoindentation and electrical resistivity measurements. PRED technique with short and high energy pulses enabled the (111) texture while increasing the forward off-time with optimized current density resulted in the formation of (100) and (101) textures. The reverse/anodic pulse applied after every forward pulse aided the minimization of residual stresses with no additives in the electrolyte, stability of texture in the foils, grain refinement and formation of growth-twins.Among the three highly textured copper foils, those with dominant (111) texture exhibited a lower electrical resistivity of ~1.65×10 -6 Ω-cm and better mechanical strength compared to those with (100) and (101) textures.

No abstract