Microstructure and properties of copper matrix composites reinforced by equal amounts of GNPs and CNTs

To address the challenge of balancing mechanical and electrical conductivity in copper matrix composites, this study explored a synergistic reinforcement strategy using graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs). Composites containing 0.1 wt% total reinforcement—pure GNPs, pure CNTs, and their hybrid (0.05 wt% each)—were fabricated by ball milling and spark plasma sintering. While the CNTs/Cu composite achieved higher tensile strength (285.12 MPa) but lower conductivity (92.54% IACS), and the GNPs/Cu composite retained high conductivity (93.94% IACS) close to pure Cu (95.40% IACS) with limited strength improvement, the hybrid system delivered the best comprehensive performance in the sintered state. After hot rolling, the hybrid composite reached a tensile strength of 414.94 MPa and an electrical conductivity of 91.68% IACS, primarily due to increased dislocation density and introduced defects. This demonstrates an effective trade-off between mechanical enhancement and conductivity retention. This work provides a theoretical basis for designing high-strength, high-conductivity copper composites.