Porosity Study of Developed Al-Mg-Si/Bauxite Residue Metal Matrix Composite Using Advanced Stir Casting Process

摘要

Bauxite residue (BR) is the waste generated from alumina processing industries, which is considered as an environmental problem throughout world. Hence, utilization of BR is the need of the hour. In the present investigation, vacuum type bottom pouring mechanism is introduced in stir casting process to fabricate a low-cost particulate metal matrix composite (PMMC) using Al-Mg-Si alloy with BR as reinforcement. Controlled process parameters in terms of stirring speed and particle percentage were chosen in development of Al-Mg-Si/BR PMMC. The result of the microstructural study reveals uniform distribution of particles with 350 and 450 rpm of stirring speed. In this study, it was observed that increased BR weight fraction resulted in increased porosity content of the developed PMMC. Porosity content was found to have major impact on the microhardness of developed Al-Mg-Si/BR PMMC. The microhardness behavior of the developed PMMC was also predicted at different indentation loads. Microstructure was examined at both stirring speeds at different cross sections of the cylindrical samples. The reinforcement content was varied in a percentage range of 2-8% by weight. Beyond the limit of 8-wt% reinforcement concentration, defects like voids, local clustering, and agglomeration of particles were seen in the developed Al-Mg-Si/BR PMMC.