## 2 Experimental Approach
Few samples with a 1.25 modulus and a 1.67 modulus revealed a variation in hardness with an applied load during compaction. This was primarily because of the varying frictional conditions between the reinforcing particles during compaction, which exerted a noticeable level of densification along the length of the chosen part. Uneven interface bonding between the chosen reinforcing SiCp and Al particles, coupled with the movement of the reinforcement clusters, caused and/or favored an intrinsic variation in the hardness. An improvement in the hardness of the cylindrical samples for a modulus of 1.67 is shown in Figure 5b. This was essentially due to a strong interface bonding between the reinforcing SiCp particles and the aluminum metal matrix. A decrease in the hardness for a part modulus of 1.87 indicated a lower densification of the aluminum matrix composite. This is also shown in Figure 5b. The correlation between the hardness and density with respect to the part modulus is shown in Figure 6. The parts sintered for 60 min to 90 min revealed a noticeable improvement in properties (quantified by density and hardness). A high density (2.7 g/cm\({}^{3}\)) with a low hardness (\(\sim\)34 HR) was observed for a part modulus of 1.87. A higher sintered density of the Al MMCs did not necessarily result in a higher hardness, as in the case of both aluminum and an aluminum alloy. This could be due to the presence of hard reinforcing particles such as SiCp. The correlation was retained for a part modulus of 1.25 and 1.67 and a sintering time of 60 min to 90 min. The sintered density achieved was 2.69 g/cm\({}^{3}\) and this was made possible by controlling both the compaction pressure and the sintering parameters; i.e., (i) the sintering temperature and (ii) the time. Moreover, increasing the sintering time and temperature could increase the density and hardness [2]. Figure 4: Effect of SiCp/Al\({}_{2}\)O\({}_{3}\)p volume fraction on the sintered aluminum matrix composites (AMCs) for the various sintering conditions. A metallographic examination and analysis of the Al MMCs was carried out to investigate the effect of changing the sintering temperature and sintering time on the distribution of the reinforcements; i.e., SiC particles in the aluminum metal matrix. Optical micrographs were taken using a LEICA DM2500M microscope. The distribution of the reinforcing SiC particles in both the aluminum matrix and the aluminum grain boundaries is shown in Figure 7 for a part modulus of 1.87. \[\rho_{AMCs}=\frac{\rho_{l}\times w_{AMCs}}{\Delta w_{AMCs}}. \tag{1}\]0 Hardness of the sintered aluminum MMCs (sintering temperature: 700 \({}^{\circ}\)C): (**a**) location of indentation on the test specimen and (**b**) variation in hardness with modulus. \[\rho_{AMCs}=\frac{\rho_{l}\times w_{AMCs}}{\Delta w_{AMCs}}. \tag{1}\]1 Correlation between hardness and density for Al/7 vol.% SiC\({}_{\text{P}}\) for the different part moduli (sintering temperature: 700 \({}^{\circ}\)C). The distribution of the reinforcing particulates was found to be changed upon increasing the sintering time. Most of the reinforcing SiC particles were located both at and along the grain boundaries. The reinforcing particles tended to gradually move along the grain boundary of the aluminum due to an increase in grain size following 90 min of sintering. Moreover, an improved distribution of the reinforcing SiC particles (SiCp) resulted in improved density and hardness following sintering for 90 min. The porosity level reduced for the sintered Al/7 vol.% SiC\({}_{\text{P}}\) with an increase in the sintering time. However, the presence of the clustering of SiC could depend on the degree of homogeneity of the particle dispersion [32].