Microstructural and property evolution of layered composites from single-crystal Cu/Gr foils during hot pressing and rolling

The incorporation of graphene (Gr) into copper (Cu) has emerged as a promising route to design Cu matrix composites with tailored properties. However, studies on the microstructural evolution of two-dimensional layered Cu/Gr composites during fabrication and rolling, as well as its influence on the resulting properties, remain insufficient. Here, monolayer Gr was synthesized on single-crystal Cu foils via chemical vapor deposition (CVD), and multiple foils were stacked and followed by vacuum hot-press sintering to fabricate bulk Cu/Gr composites. The evolution of Gr integrity, dislocation density, grain size, texture, and recrystallization behavior during rolling and annealing was systematically investigated, alongside a comprehensive evaluation of mechanical and electrical performance. In the hot-pressed state, the composites exhibit a distinct layered structure, with grain size largely inherited from the initial single-crystal foils, though localized Gr agglomeration and defects are observed. Increasing the rolling reduction to 90 % enhances the tensile strength from 202 MPa to 410 MPa, while the electrical conductivity decreases from 100.5 % IACS to 97.5 % IACS, and the elongation drops from 64.6 % to 5.6 %. Subsequent annealing mitigates strength while partially restoring ductility and conductivity, with fractured Gr interfaces serving as effective grain boundary pinning sites. These findings reveal the coupled effects of Gr incorporation and thermomechanical processing on microstructure–property relationships, offering new insights into the design of high-performance Cu/Gr composites.