Metal matrix composites (MMCs) are new materials, which are very essential for industry manufacture applications, such as automotive, aerospace and military. So far, an enhancement of the MMCs hardness has been interestingly studied. In this paper, we study the formation of Al-5%Cu-4%Mg matrix with the reinforcement of SiC by thixoforming process. Several important parameters for increasing the MMCs hardness, such as volume fraction of reinforcement, ageing time and temperature, are investigated. It is found from the microstructure analysis that the distribution of SiC particles is homogen for both MMCs with 5 vf.% SiC and 10 vf.% SiC. We also found fine, globular and non-dendritic structures, indicating that an appropriate structure of thixoforming process is obtained. From the hardness measurement, the hardness values are influenced by the reinforcement, thixoprocess and ageing. Our experimental results indicates that such parameters have to be considered in order to obtain the optimum performance of Al- 5%Cu-4%Mg matrix.