Designing 1D Undulating Graphene for Enhancing Mechanical Properties in Cu Matrix Composites

Conventional chemical functionalization strategies intended to enhance graphene/Cu interfacial bonding often compromise the intrinsic properties of graphene. Here, we integrate ball milling with in situ synthesis to embed 1D carbon nanotubes (CNTs) into multilayer graphene, replacing chemical interfacial modification with a physical meshing interface—1D undulating‐structural graphene (CNTs@Gr), which preserves graphene integrity and ameliorate Gr–Cu matrix coupling. The Cu matrix composite possessing optimized interface structure, which is associated with the CNT content and outer diameter, achieves exceptional strength‐ductility synergy, displaying a yield strength of 301 MPa and an ultimate tensile strength of 341 MPa, as well as a remarkable elongation‐to‐failure of 17.8% for 0.25CNTs(m)@Gr/Cu composite. Meanwhile, the CNTs@Gr facilitates dislocation pile‐up, graphene‐induced crack deflection and CNTs crack‐bridging, dominating the stable plastics deformation. Furthermore, by circumventing the detrimental impacts inherent to conventional interface modification strategies, the structurally intact graphene and contamination‐free interface effectively preserve the material's electrical conductivity, which remains at a high level of 90.7% IACS. This work unlocks the reinforcing potential of interface engineering and opens a novel avenue for improving mechanical properties and electrical conductivity.