The Effect of TiB ₂ on Mechanical and Microstructural Properties of AZ91 Matrix Composites Manufactured by Cold Chamber Die Casting Process

In these work AZ91 magnesium matrix composites reinforced with two weight fractions (5 and 10 wt. %) of TiB₂ particulates were fabricated by cold chamber die casting process technique. The microstructure, density, hardness, mechanical properties of the specimens was investigated. Microstructure studies showed that fairly uniform distribution of reinforcements was achieved up to the weight fraction studied. As compared to base alloy AZ91, the hardness and tensile strength considerably increased with increasing reinforcement content. The presence of TiB₂ particles improved the hardness around 24.4 %, compressive strength around 67.2% and the yield strength around 20%. The enormous amount of increment in the compressive strength due to the dislocation density created by the difference in thermal properties of matrix and composites and also due to the micro-pores presence in the composite.