# Advancing Copper Wire Technology: Graphene/Cu Composites for Superior Conductivity and Strength
## 3 Results and Discussion
Figure 2: Structural characterization of Gr/Cu composite powder: (**a**) XRD pattern and (**b**) Raman pattern. enhanced electrical pathways. Thus, the observed morphologies and surface characteristics of each variant are not only indicative of their synthesis processes but are also critical in determining their suitability for specific industrial applications. High-resolution transmission electron microscopy (HRTEM) was utilized to delve into the graphene coatings and detailed structural characteristics of various Gr/Cu composite powders, providing valuable insights into their composition and potential applications. The HRTEM analysis of Gr/Cu-Z powder demonstrated graphene coatings on dendritic particles (Figure 4a,b). From Figure 4c (corresponding to the red square area in Figure 4b), it can be observed that the graphene thicknesses ranging from 0.3 to 0.8 nm and configurations predominantly in single and bilayer forms. In contrast, the Gr/Cu-T powder displayed clear graphene striations on spherical particles (Figure 4g,h), with the graphene layers being approximately five layers thick, indicative of multilayer graphene (red dotted area in Figure 4i). Energy-dispersive X-ray Spectroscopy (EDS) was used to test the distribution of C and Cu elements in the sample, as illustrated in Figure 4d-fj-l, confirming the homogeneous distribution of carbon across the copper particles, evidencing effective graphene encapsulation within the composites. This encapsulation is vital for maintaining the integrity and enhancing the performance of the composites in various applications. The findings from the HRTEM analysis closely align with earlier Raman spectroscopy results, which pointed to varying degrees of graphene layering between the two powder types. Overall, the detailed analysis from HRTEM not only corroborates previous findings but also underscores the critical role of graphene encapsulation and layering in determining the functional capabilities of these composite powders. The fabrication of Gr/Cu composite copper wire samples involved a series of processes including hot pressing, drawing, and annealing, aimed at integrating graphene into the copper matrix to enhance its properties. SEM images of these annealed samples revealed significant textural differences between pure copper wires and Gr/Cu composites, as exhibited in Figure 5. Pure copper wires displayed a smooth, fibrous texture devoid of pores or defects, indicative of a densely fabricated material (Figure 5a,b). In contrast, both types of Gr/Cu composite wires--Gr/Cu-Z and Gr/Cu-T--maintained the fibrous structure but exhibited a rougher surface with dark regions, which are suggestive of graphene clusters (Figure 5c-f). Notably, the Gr/Cu-T composite wire showed more pronounced dark regions, indicating a higher content of graphene. Figure 3: SEM characterization of various Gr/Cu composite powders: (**a–c**) Gr/Cu-Z, (**d–f**) Gr/Cu-T.  
Further metallographic analysis (Figure 6a-c) provided insights into the microstructural changes induced by the addition of graphene. The grain size distribution of the composite is shown in Figure 6d. Pure copper samples had an average grain size of 4.2 \(\upmu\)m, whereas the Gr/Cu-Z and Gr/Cu-T composites showed reduced grain sizes of 3.2 \(\upmu\)m and 2.5 \(\upmu\)m, respectively. This reduction in grain size, particularly noted in the Gr/Cu-T wires with no grains observed over 20.0 \(\upmu\)m, suggests that graphene acts as an inhibitor to grain growth. The implications of these findings are significant. The addition of graphene not only alters the microstructure by reducing the grain size but also correlates with the amount of graphene added, as seen in the differences between the Gr/Cu-Z and Gr/Cu-T compos  
Figure 4: Microstructure characterization of various Gr/Cu composite powders: TEM images (**a–c**) and element distribution maps (**d–f**) of Gr/Cu-Z composite powder; TEM image (**g–i**) and element distribution map (**j–l**) of Gr/Cu-T composite powder. ites.