Experimental Analysis of Microstructure and Mechanical Properties of Aluminum Metal Matrix Composite Reinforced with Different Materials

This work reports on the synthesis and characterization of novel aluminum-based hybrid metal matrix composites (MMCs) reinforced with combinations of titanium (Ti), nickel (Ni), and magnesium (Mg) by a stir casting process. Three compositions (all having 88 wt.% Al and 12 wt.% total reinforcement) were prepared: (i) 88Al–5Ti–4Ni–3Mg, (ii) 88Al–4Ti–3Ni–5Mg, and (iii) 88Al–3Ti–5Ni–4Mg. The microstructure was examined by scanning electron microscopy (SEM), and mechanical properties were measured via Brinell hardness, uniaxial tensile, and Charpy impact tests. Results show effective incorporation of the ceramic/metallic reinforcements into the Al matrix with generally uniform particle distribution. The composite containing 5 %Ti–4 %Ni–3 %Mg (case i) exhibited the highest ultimate tensile strength (≈270 MPa) and impact strength (≈3.1 J/cm²), whereas the sample with 3 %Ti–5 %Ni–4 %Mg (case iii) achieved the greatest Brinell hardness (≈70 BHN). Increasing Ni content tended to refine the microstructure (reducing average grain size from ~0.96 µm to 0.83 µm) and raised hardness, but higher Ni also slightly reduced ductility. The findings demonstrate that hybrid reinforcement can significantly enhance hardness and strength of Al alloys, consistent with known MMC behavior. Such light-weight composites with tailored Ti/Ni/Mg ratios show promise for high-strength applications in aerospace and automotive sectors.