Effect of TiO ₂ on physical and thermo-mechanical properties of Al6061-5ZrO ₂ hybrid composites

Aluminum matrix composites based on Al6061 have attracted considerable attention for lightweight structural applications due to their favorable strength-to-weight ratio and good corrosion resistance. Although several studies have investigated Al6061 composites reinforced individually with ZrO 2 or TiO 2 , systematic studies on hybrid composites containing both reinforcements remain limited. In particular, the combined influence of ZrO 2 and TiO 2 , on the physical and thermo-mechanical properties of Al6061-based composites has not been fully explored. In this study, Al6061–5wt.% ZrO 2 hybrid composites reinforced with varying TiO 2 content (0–12 wt.%) along with minor additions of SrO and Y 2 O 3 were fabricated using the stir casting technique. The developed composites were characterized in terms of microstructure, density, porosity, and thermo-mechanical properties. The results demonstrated that a remarkable improvement in density (2.6521 to 2.6719 g/cc), and hardness (74 to 94 HV) were ascertained. Whereas, tensile strength, tensile modulus, impact strength, compressive strength, fracture toughness enhanced with 0 to 8 weight percent TiO 2 reinforcement, and upon further increasing the TiO 2 weight percentage these properties reduced. Thermal conductivity demonstrated a decreasing trend from 127.9 to 119.4 W/m-K with TiO 2 reinforcement. The microstructural studies were carried using SEM. The composites reinforced with 8wt.% TiO 2 exhibited the best combination of mechanical properties. This novel and all-encompassing commonality across all the investigated properties for complex microstructures may prove useful in developing superior composite structures and other high-performance engineering applications.