Effects of TiO2 powder morphology on the mechanical response of pure magnesium: 1D nanofibers versus 0D nanoparticulates

A novel attempt is made to study and compare the effects of TiO2 morphology in the form of nanoparticulates and nanofibers on the physical, mechanical and microstructural properties of pure magnesium. Pure magnesium and Mg (1.98 and 2.5) vol. % TiO2 nanocomposites are synthesized by powder metallurgy technique coupled with microwave sintering followed by hot extrusion. X-Ray diffraction studies of the synthesized magnesium materials indicated that morphology of ultrafine reinforcements play a vital role in modifying the strong basal texture of pure magnesium. The microstructural characterization of Mg-TiO2 nanocomposites indicated significant grain refinement of pure Mg with TiO2 nanoparticulates contributing more effectively exhibiting as high as 22% reduction observed with Mg 2.5 vol. % TiO2 nanocomposite having TiO2 in the form of nanoparticulates. Under tensile loading, with addition of 1.98 vol. % TiO2 nanoparticulates and nanofibers, significant improvement in the tensile fracture stain of pure magnesium of ∼14.5% and ∼13.5%, respectively was observed. Further, marginal changes in the tensile strength of pure magnesium by ∼10 MPa was observed with the addition of TiO2 reinforcements. Under compression loading, among the synthesized magnesium materials, Mg-TiO2 nanocomposites containing 1.98 vol. % TiO2 nanofibers exhibited superior strength properties with a maximum 0.2% compressive yield strength and ultimate compressive strength of ∼90 MPa and ∼300 MPa, respectively. Further, decrease in the tension-compression asymmetry values was found to be more significant in Mg-TiO2 nanocomposites where TiO2 was used in the fiber form. The results reveal that TiO2 nanofiber is more effective in improving the overall mechanical performance of pure magnesium.