Synergetic optimization of strength and electrical conductivity in graphene/Cu wire with bimodal grain size distribution

In this study, graphene (Gr)/Cu wires with unimodal and bimodal grain size distributions were prepared by cold-drawing process. The relationship between microstructure evolution, mechanical properties, and electrical conductivity was systematically studied. In the fabricated wires, the bimodal grain structure is more conducive to the formation of high-density nano twins and 9 R phase, which can significantly improve the tensile strength while maintaining high electrical conductivity. This work not only demonstrates that bimodal grain design enables a superior strength-conductivity synergy (730 MPa and 91% IACS at ε=10.6), but also establishes a complete structure-property relationship from hetero-deformation–induced effect to planar defect engineering, providing a distinct pathway beyond the conventional decoupling or interface modification strategies for overcoming the strength-conductivity trade-off in copper matrix composites.