Superplastic Deformation of Cold-Rolled Ni-Graphene Oxide Nanocomposites Foils

This study investigates the superplastic deformation of a cold-rolled Ni/Graphene Oxide composite foil, with a particular emphasis on the mechanism that enhances the two-dimensional ultra-thin phase graphene oxide (GO). The findings reveal that intergranular fracture takes place due to a larger plastic strain in the radial direction than in the tangential direction. Furthermore, the reinforcing phase GO tends to become fibrous after rolling, with the fiber direction oriented along the radial direction. The size of matrix grains surrounded by GO does not significantly increase at high temperatures. However, during stretching, the formed voids expand along the matrix and both ends of the GO. The formation and aggregation of voids increases the likelihood of high-temperature tensile fracture of the foil, ultimately resulting in a lower elongation of Ni/GO after rolling when compared to the original foil. The two-dimensional flexible reinforcement phase tends to transform from sheet-like to fibrous. When an external force is applied, it causes the multi-layer stacked GO to appear tense, which is visually observed for the first time.