Investigation into the mechanical properties of heat-treated magnesium metal matrix composites reinforced with TiO₂ and Sn particles

This study explores the development and analysis of magnesium-based metal matrix composites reinforced with titanium dioxide (TiO₂) nanoparticles and tin (Sn) micro-particles. Employing the AZ31 alloy as the substrate material, these composites are fabricated using the bottom pouring stir-casting method. The research aims to assess the microstructural characteristics, micro-hardness, and tensile behavior of the AZ31 alloy and its composites, which feature 1.5 wt% TiO₂ nanoparticles and varying levels of tin (Sn) content. Optical microscope analysis reveals uniform dispersion of TiO₂ particles throughout the matrix, with noticeable clustering along grain boundaries. Grain size reduction is observed upon Sn addition, potentially contributing to improved mechanical properties. Microhardness testing shows enhanced hardness in TiO₂-reinforced composites, attributed to TiO₂ nanoparticles’ reinforcing effect and tin’s solid solution strengthening. Tensile testing significantly enhances ultimate tensile strength (UTS) and yield strength with TiO₂ reinforcement, increasing Sn content to 6 wt%. However, excessive Sn addition (> 6 wt%) increases porosity and particle clustering, decreasing tensile characteristics. The altered textural properties induced by TiO₂ nanoparticles contribute to improved tensile properties, while excessive Sn content leads to brittle fracture behaviour. This study provides valuable insights into the microstructural and mechanical behaviour of AZ31-based composites, offering guidance for future composite material design and optimization.