## 3 Results and Discussion
### Micro-Hardness Evaluation  
The micro-hardness values of behaviors of the Cu-SiC-Gr and Cu-WC-Gr hybrid composites in comparison to the base copper matrix are summarized in Figures 9 and 10, respectively. It was found that the addition of hard and stiff reinforcements contributed to the improvement of the hardness of the copper composites. The microhardness value of the base alloy was found to be 128 HV. It is important to note that the maximum hardness value was observed in the case of 9 wt.% SiC-Gr and 9 wt.% WC-Gr composites in comparison to the base matrix. However, WC-Gr reinforced hybrid composites had more hardness value than the SiC-Gr composites. The Cu-9%SiC-1%Gr composites witnessed a microhardness  
Figure 8: XRD phase analysis of Cu alloy and Cu-(\(3,6,9\)) wt.% WC-Gr hybrid composites.  
Figure 7: XRD phase analysis of Cu alloy and Cu-(\(3,6,9\)) wt.% SiC-Gr hybrid composites.  
value of 164 HV, whereas the Cu-9%WC%-1%Gr composites exhibited a value of 174 HV. Further, the Cu-9%SiC-1%Gr composites revealed an increment of 28% in comparison to the base alloy, whereas the Cu-9%WC-1%Gr had shown a 36% increase in hardness property. Both SiC and WC are considered to be hard constituents, and their further addition led to a significant enhancement of the hardness of the composites. Various factors resulted in the strengthening of the hybrid composites. Primarily, it is associated with the uniform distribution of the ceramics particulates in the soft copper matrix. Similarly, the hard reinforcements caused resistance to deformation during the indentation. Moreover, the interfacial strength of the SiC and WC with copper matrix improved the hardness properties of the composites by transferring the load to the reinforcement particles. The well-dispersed SiC and WC particles occupied the interstitial position in the copper alloy, therefore, restricting the local deformation and crack growth in the composites. A sample image of the indentation during the Vickers micro-hardness testing is presented in Figure 11. Several previous works of literature also reported similar results. [PERSON] et al. [14] examined the mechanical characteristics of the Copper hybrid composites reinforced with titanium dioxide and graphite produced through stir casting, which resulted in the enhancement of the hardness. Similarly, the Cu matrix reinforced with TiB\({}_{2}\) particulates exhibited higher hardness due to the homogeneity in distribution with less porosity in the composites [23]. Moreover, the 10 wt.% silicon carbide reinforced Cu-Sn alloy composites witnessed the maximum enhancement of 50% (approx.) in the hardness behavior due to the Orowan strengthening and particle strengthening mechanism [24]. The Orowan mechanism is applicable in the case of the MMCs, where the reinforcements are nano and sub-micron levels. Similarly, [PERSON] et al. [25] investigated the hardness properties of copper hybrid composites by powder metallurgy route. They reported that the Orowan mechanism had contributed more to the increase in the hardness behavior of the composites due to the less inter-particle spacing for the fine reinforcement particles.  
Figure 9: Variation of Vickers micro-hardness Cu alloy and Cu-(3, 6, 9) wt.% SiC-Gr hybrid composites.