Effects of Primary Processing Techniques and Significance of Hall-Petch Strengthening on the Mechanical Response of Magnesium Matrix Composites Containing TiO₂ Nanoparticulates.

In the present study, Mg (1.98 and 2.5) vol % TiO₂ nanocomposites are primarily synthesized utilizing solid-phase blend-press-sinter powder metallurgy (PM) technique and liquid-phase disintegrated melt deposition technique (DMD) followed by hot extrusion. Microstructural characterization of the synthesized Mg-TiO₂ nanocomposites indicated significant grain refinement with DMD synthesized Mg nanocomposites exhibiting as high as ~47% for 2.5 vol % TiO₂ NPs addition. X-ray diffraction studies indicated that texture randomization of pure Mg depends not only on the critical amount of TiO₂ NPs added to the Mg matrix but also on the adopted synthesis methodology. Irrespective of the processing technique, theoretically predicted tensile yield strength of Mg-TiO₂ nanocomposites was found to be primarily governed by Hall-Petch mechanism. Among the synthesized Mg materials, solid-phase synthesized Mg 1.98 vol % TiO₂ nanocomposite exhibited a maximum tensile fracture strain of ~14.5%. Further, the liquid-phase synthesized Mg-TiO₂ nanocomposites exhibited higher tensile and compression properties than those primarily processed by solid-phase synthesis. The tensile-compression asymmetry values of the synthesized Mg-TiO₂ nanocomposite was found to be lower than that of pure Mg with solid-phase synthesized Mg 1.98 vol % TiO₂ nanocomposite exhibiting as low as 1.06.