In-situ generated graphene from wheat flour for enhancing mechanical and electrical properties of copper matrix composites

Graphene, with its excellent mechanical properties and electrical conductivity, has been considered as an effective reinforcement phase for copper matrix composites. However, due to its easy agglomeration and poor wetting properties in the copper matrix, it is difficult to simultaneously enhance strength, ductility and conductivity of graphene matrix copper composites using a low cost and efficient method. In this paper, we proposed a new methodology to use wheat flour as a solid carbon source to in-situ generate graphene-coated copper (Gr@Cu) composite powders. These powders were then used as strengthening phases to fabricate Gr@Cu copper composites through wet mixing and spark plasma sintering (SPS) processes. Results showed that not only high-quality graphene layer was obtained and serious agglomeration of graphene was avoided, but also a strong interfacial bonding between graphene and copper matrix was achieved. The fabricated composites showed excellent properties, e.g., a maximum density of 99%, enhanced micro-hardness (15%–22% higher than that of pure copper), and excellent strength/ductility. The maximum tensile strength and yield strength were obtained in the 0.70 wt.%Gr@Cu/Cu composites (e.g., 252 MPa and 132 MPa, respectively). These values are ∼23% and ∼110% higher than those of pure copper, and the elongation rate was maintained at ∼30%. In addition, the composites showed excellent conductivity. • Wheat flour was used to in-situ generate Gr@Cu composite powder. • Gr@Cu/Cu composites achieve high strength/ductility and good conductivity. • Interfaces of Gr@Cu/Cu composites have strong bonding, providing load transfer.