Parametric behaviour optimisation of macro and micro hardness for heat treated Al 6061-red mud composite

Abstract

Composite with aluminium 6061 matrix using red mud reinforcement to reduce the cost have been fabricated by stir casting method. A stirring arrangement has been used to ensure the uniform distribution. Scanning electron microscopy has been used to verify the uniform distribution of the reinforcement particles and energy dispersive spectroscopy has been used to confirm the presence of reinforcement inside Aluminium 6061 matrix. Macro Hardness has been obtained using Rockwell hardness tester at 60 kg load by using 1/8 inch steel ball at H scale and Vickers micro hardness measured using Vickers micro-hardness tester. The results have been analysed by applying Taguchi technique. The value of macro hardness and micro hardness has been found to be increased with an increase in percentage of reinforcement and ageing time, while it shows a reverse trend with increase in particle size of the reinforcement. The ANOVA analysis of the data observes that the ageing time has significant effect and particle size has least effect on both macro and micro hardness of the developed composite. Further, the experimental and predicted results have been found in close proximity to each other. Keywords: Metal matrix composite, Red mud, Aluminium 6061, Hardness, Stir casting