Influence of Nickel Addition and Effect of Heat Treatment on Aluminium-Silicon Piston Alloys

The present study was performed on Al-Si-Cu-Ni-Mg piston alloy to investigate the effect of nickel addition and heat treatment on the microstructure and mechanical properties of the alloy. Piston alloys are, a group of Al-Si cast alloys alloyed with the elements such as copper, magnesium and nickel, widely used for the production of pistons of internal combustion engines by virtue of their low thermal expansion coefficient and high wear resistance. The microstructure and properties of these alloys are very much dependent on the casting technique, composition, cooling rate, and heat treatment. In this study, five near-eutectic piston alloys with varying nickel additions were employed using gravity-die casting method. T6-Heat treatment has been carried out on the samples to observe the effect of heat treatment on microstructures and mechanical properties such as tensile strength and hardness. The alloy having better microstructural features and mechanical properties has been selected and XRD analysis has been conducted to identify different phases presented in this alloy. SEM analysis of the fractured surfaces of tensile testing specimens have been conducted to study the mode of fracture occurred in the alloy. Optimum aging time of the developed alloy has been standardized by wear analysis and hardness evaluation at different aging time.