Mechanical and microstructural properties of TiO₂-enhanced magnesium composites prepared by powder metallurgy

This study investigates the formulation of magnesium-based nanocomposites reinforced with titanium dioxide (TiO₂) nanoparticles at four different volume fractions (0.5, 1.5, 3, and 5 vol%) by powder metallurgy. Based on SEM and EDX, the microstructural observation confirmed an overall uniform (TiO₂) distribution in Mg matrix, which resulted from the successful incorporation, resulting in a considerable grain refinement (reaching a minimum size of 340 nm in the 3 % TiO2 material). The presence of Mg, MgO, and TiO 2 phases was verified with X-ray diffraction (XRD). The density and porosity had been affected progressively by the amount of TiO 2 . Hardness increased continuously with mechanical analysis and its maximum value was reached at 5 vol% TiO 2 . The compressive strength rose to an optimal value at 3 vol% (up to 208 MPa) and declined at 5 vol% attributed to the simultaneous mechanism of increased porosity and particle clustering, but still higher than pure Mg. The stronger performance was mediated mainly by synergistic contributions of various processes: grain refining (Hall-Petch effect), Orowan looping in TiO2 hard particles, effective load transfer across matrix-reinforcement interface, and dislocation strengthening effect due to thermal expansion mismatch (CTE). It is confirmed by this study that 3 vol% TiO 2 content is the optimal combination between the strengthening mechanisms and the process restrictions for the powder metallurgy Mg-based nanocomposites. • Magnesium-based nanocomposites reinforced with TiO₂ nanoparticles were successfully fabricated using powder metallurgy. • A two-stage sintering process improved particle bonding and reduced porosity in the composite structure. • Optimal mechanical performance was achieved at 3 vol% TiO₂, enhancing compressive strength by ∼24 %. • Uniform dispersion of TiO₂ nanoparticles was confirmed using FE-SEM and EDS mapping. • Grain refinement and Orowan strengthening mechanisms contributed significantly to hardness and strength improvement.