Effect of Mg/nano-Al 2 O 3 interaction time during stirring on microstructure and mechanical properties of Mg–Al 2 O 3 composite

Abstract

In the present study, magnesium based composites containing 1·1 vol. of alumina particulates at nanolength scale were synthesised using disintegrated melt deposition technique. The main focus was to vary interaction time between molten magnesium and nano-Al₂O₃ particulates during stirring and to study its effects on the microstructure and mechanical properties. With an increase in stirring time, microstructural characterisation of the composite materials revealed reasonably uniform distribution of Al₂O₃ reinforcement, marginal grain refinement and presence of minimal porosity. Mechanical properties characterisation revealed that an increase in stirring time led to a simultaneous increase in hardness, 0·2 yield strength and ultimate tensile strength while ductility was compromised beyond 7·5 min stirring when compared to pure Mg. The optimal stirring time is observed to be in 5–7·5 min range in order to realise the best combination of strength, hardness, ductility and work of fracture.