Mechanical Behaviour and Microstructural Insights of ZE42 Magnesium Alloy Reinforced with Hybrid TiO₂ and Graphene Nanoplatelets

Magnesium matrix composites usually face challenges from poor wettability, agglomeration of nano-reinforcements and weak interfacial bonding between the reinforcements and a metal matrix which limits their mechanical and tribological properties. This study aims to improve microstructure and mechanical performance of magnesium alloy ZE42 through hybrid reinforcement of TiO₂ nanoparticles and GNPs. Composites with varying reinforcement contents were made using the stir casting process, under precisely controlled processing conditions. Microstructural characterization using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction confirmed grain refinement, effective incorporation, and relatively uniform distribution of reinforcements within the magnesium matrix. The mechanical testing indicated remarkable increases in hardness, tensile strength and compressive strength, also confirmed by wear tests that show a lower value of friction and increase in wear resistance because of the synergistic effect based on dispersion strengthening and solid lubrication. Across all compositions, the highest GNP content hybrid (S4) composite demonstrated superior performance. The findings reveal that TiO₂–GNP hybrid reinforcement is an efficient approach for optimizing the wear and friction properties of ZE42 magnesium alloy, making it a promising material for lightweight engineering applications.