# Advancing Copper Wire Technology: Graphene/Cu Composites for Superior Conductivity and Strength
## 3 Results and Discussion
Graphene not only improves electron transfer channels but also increases mechanical strength through these crucial microstructural modifications. Notably, the Gr/Cu-T composite wire exhibits marginally better overall performance than Gr/Cu-Z, likely due to subtle differences in graphene content or distribution. However, these findings also highlight the need for further research to optimize graphene content and distribution within the composites. Such in-depth studies are essential to fully exploit the potential benefits of graphene in enhancing the performance of copper wires, suggesting that continued refinement in the processing and integration of graphene is necessary. The examination of fracture morphology in both pure copper and graphene-enhanced composites has yielded insightful differences that underscore the impact of graphene on the mechanical properties of copper wires. As shown in Figure 10a-i, all wire samples exhibit noticeable dimples on the fracture surfaces after annealing, indicating that the fractures are ductile in nature. In pure copper, the fracture surface was characterized by equiaxed dimples, reflecting a ductile fracture with a uniform size distribution of micropores indicative of material superior toughness (Figure 10a-c). However, upon the introduction of graphene, the fracture surfaces of the composites exhibited a transformation in dimple morphology; they became more heterogeneous and shallower with increased density (Figure 10d-f), suggesting a higher load-bearing capacity. Specifically, the Gr/Cu-T composite wire displayed the most substantial change in dimple characteristics among the composites (Figure 10g-i). Figure 9: Performance comparison of annealed composite wires: (**a**) conductivity, (**b**) tensile strength, and (**c**) comparison of pure Cu wires or Gr/Cu composite wires fabricated by other methods reported in the literature [8; 20; 36; 37; 38; 39; 40; 41]. It showed the highest number of dimples, which were also the smallest, correlating closely with the smallest grain sizes observed among the composites. This suggests that finer grain sizes contribute to enhanced mechanical properties. Additionally, graphene within these composites appeared as pull-outs in the dimples, with the flakes being thinner and smaller compared to other samples, indicating a good dispersion state of graphene that facilitates load transfer. The conclusions drawn from these observations highlight that the addition of graphene significantly alters the fracture mechanics of copper wires. The more heterogeneous and densely packed dimples enhance the load-bearing capacity, while the distribution of graphene at the interface and within the copper matrix improves load transfer capabilities, significantly increasing the tensile strength of the material. The intrinsic mechanisms by which the interfacial interactions between graphene and copper enhance mechanical and electrical properties can be investigated using techniques such as X-ray photoelectron spectroscopy and/or X-ray absorption spectroscopy [43; 44]. Notably, the Gr/Cu-T composite wire exhibits superior mechanical properties, likely due to optimal graphene dispersion and effective grain size reduction. These findings emphasize the beneficial role of graphene in reinforcing copper composites, suggesting that the optimal integration of graphene is crucial for maximizing mechanical performance.