Mechanical properties and fractography of zircon-particle-reinforced ZA-27alloy composite materials

The mechanical properties and the fracture mechanism of composites consisti ng of ZA-27 alloy reinforced with Zircon particles were investigated with t he primary objective of understanding the influence of the particulate rein forcement on the behaviour of the ZA-27 alloy. The zircon particle content in the composites ranged from 1 to 5%: in steps of 2%by weight. The composi tes were fabricated by the 'compocasting' technique in which the molten mas s was squeeze-cast under pressure. The study revealed improvements in ultim ate tensile strength, yield strength, hardness, and Young's modulus of the composites, but at the cost of ductility and impact strength, which decreas ed with increase in zircon content. The fracture behaviour of the composite s was altered significantly by the presence of the zircon particles, crack propagation through the matrix and the reinforcing particles resulted in th e final fracture. Scanning electron microscopy and fractography analyses ha ve been carried out to furnish suitable explanations for the observed pheno mena.,(C) 1999 Elsevier Science Ltd. All rights reserved.