Influence of reinforcement on microstructure and mechanical response of a magnesium alloy

Reinforcement of magnesium alloys with ceramic particulates has engineered a new family of materials that are marketed under the trade name metal-matrix composites. Rapid strides in the processing of these materials during the last two decades have provided the necessary impetus for their emergence and use in structural and automotive-related components. In this article we report the results of a study aimed at understanding the role of particulate reinforcements on the tensile, compressive, impact deformation and overall fracture behaviour of magnesium alloy discontinuously-reinforced with siliconcarbide particulates and saffil alumina short fibres. An increase in reinforcement content was observed to have a marginal influence on strength and detrimental influence on ductility compared to the un-reinforced counterpart. Micro-cracking in the metal matrix coupled with failure of the reinforcing phase (i.e. particulates or shortfibres), both independently dispersed and in clusters, dominated the fracture sequence at the microscopic level. The deformation and final fracture behaviour of the composite materials are discussed in light of the concurrent and mutually interactive influences of microstructural effects; deformation characteristics of the composite constituents,nature of loading and local stress state.