Mechanical properties and fracture mechanism of ZA-27/TiO2 particulate metal matrix composites

Abstract

The mechanical properties and the fracture mechanism of composites consisting of ZA-27 alloy reinforced with titanium dioxide particles were investigated with the primary objective of understanding the influence of the particulate reinforcement on the mechanical behaviour of the ZA-27 alloy. The titanium dioxide particle content in the composites ranged from 0 to 6 per cent, in steps of 2 wt %. The composites were fabricated by the stir casting technique in which the reinforcement particles were dispersed in the vortex created in the molten matrix alloy. The study revealed improvements in Young's modulus, ultimate tensile strength (UTS), compressive strength, yield strength and hardness of the composites as the titanium dioxide content was increased, but at the expense of ductility and impact strength. The fracture behaviour of the composite was also significantly influenced by the presence of titanium dioxide particles. Eventual fracture was a result of crack propagation through the matrix as well as through the reinforcing particles. Scanning electron microscopy and fractography analyses were carried out to provide suitable explanations for the observed phenomena.