Synthesis, microstructure and hardness of Al 7075/B4C/Fly-ash composite using stir casting method

Abstract

Stir-casting is the appropriate and economical technique for HAMCs synthesis as it produces uniformly reinforcement distributed composite retaining finer grains. In the present work, Al 7075/x%wt.B4C/2%wt. fly-ash HAMCs were fabricated via stir casting route, where x is weight percentage of boron carbide (x = 2, 4, 6 and 8 wt%). Incorporation and distribution of reinforcement particles in HAMCs were analysed using scanning electron microscope (SEM) and optical micrographs. Also, Micro-hardness tests were conducted at seven locals points in hardness specimen to see the variation of hardness values. The coefficient of variation was calculated to ensure uniform hardness values, which further confirm the uniform distribution of reinforcements in the prepared composite. Moreover, mathematical modelling was done to obtain the empirical relation of micro-hardness of composite with respect to fly-ash and boron carbide content, which shows the correlation between the micro-hardness and reinforcements contents in the HAMC. The synthesized HAMCs may be suitable in automobile and aerospace application where low cost, lightweight, high temperature resistant and high wear resistant composite are required.