# Advancing Copper Wire Technology: Graphene/Cu Composites for Superior Conductivity and Strength
## 3 Results and Discussion  
Figure 1 illustrates the schematic of the fabrication process for annealed Gr/Cu composite wire samples, which involves vacuum hot pressing of Gr/Cu powders synthesized by various methods, followed by drawing and annealing to yield the final Gr/Cu composite wire samples. The final annealing process is aimed to eliminate internal stresses within the material and further improve the conductivity of the material. A systematic analysis was conducted to explore the structural evolution and performance changes of the Gr/Cu composites. Initially, the structural composition of the Gr/Cu composite powders was thoroughly analyzed using XRD and Raman spectroscopy to determine the purity and structural integrity of the materials. XRD analysis revealed that both Gr/Cu-Z and Gr/Cu-T powders exhibit diffraction peaks at 43.5\({}^{\circ}\), 50.5\({}^{\circ}\), and 74.1\({}^{\circ}\), corresponding to the (111), (200), and (220) planes of pure copper, respectively, confirming the high purity of the copper in these composites, as shown in Figure 2a. Notably, Gr/Cu-Z displayed a more pronounced orientation at the (200) plane compared to Gr/Cu-T, which might influence the texture and thereby the anisotropic properties of the composite material. Figure 2b shows the Raman spectroscopy of the samples, which provided additional insights into the graphene within the powders. Both types showed weak D peaks near 1350 cm\({}^{-1}\), indicative of minimal defects in the graphene, which is crucial for maintaining high-quality structural and functional properties [29]. The intensity ratios of the 2D peak to the G peak differed between the powders, with Gr/Cu-T showing a ratio of 1.5, suggesting multilayer graphene, and Gr/Cu-Z having a ratio of nearly 2.0, which indicates graphene closer to a monolayer [30]. The combined findings from XRD and Raman spectroscopy underscore the high purity and quality of the copper and graphene used in these composites. The distinct (200) plane orientation in Gr/Cu-Z and the variations in graphene layering between the powders could significantly impact their mechanical and electrical performance. Specifically, the quality and number of layers of graphene in composite materials have a strong influence on electron transport performance. These differences highlight the critical role of structural composition in determining the functional characteristics of graphene/copper composites. SEM was employed to investigate the morphology and texture of two different Gr/Cu composite powders, identifying key distinctions that could influence their application and processing, as depicted in Figure 3. The SEM analysis of the Gr/Cu-Z variant revealed dendritic particles of approximately 5.0-10.0 in size with a slightly rough surface texture (Figure 3a-c). This texture and minor interparticle adhesion suggest a degree of clustering or agglomeration, which can be indicative of the specific solidification or aggregation processes during manufacturing. Conversely, the Gr/Cu-T variant was characterized by dispersed spherical particles of around 5.0-40.0 in size, with distinctive surface features, including prominent graphene folds and nano-sized Gr/Cu composite particles attached to their surfaces (Figure 3d-f). These features suggest more complex surface interactions and a potentially enhanced interface within the material. From these findings, it is concluded that the morphological differences, such as the dendritic versus spherical shapes, may significantly impact the mechanical properties and packing density of the materials in bulk applications. The rough texture and adhesion of the Gr/Cu-Z powder could affect its flowability and compaction in processes such as additive manufacturing, while the unique surface features of Gr/Cu-T, including the graphene folds and attached nanoparticles, might provide advantages in applications requiring increased surface area, such as catalysis or applications necessitating  
Figure 1: Preparation route of Gr/Cu composite wire sample.