Effect of mixing method and particle size on hardness and compressive strength of aluminium based metal matrix composite prepared through powder metallurgy route

Properties of metal matrix composites (MMCs) are affected by various process variables such as particle size of powders, the proportion of reinforcement material, mixing methods, sintering temperature, and duration. The significant drawback of stir casting is reinforcement segregation, which is too difficult to avoid. Hence, the powder metallurgy route is utilized to prepare Al-MMC. In the current work, aluminium-based MMC is fabricated with varying proportions of silicon carbide (SiC) as a reinforcement material. Mixing of powders is done using V-Blender and barrel mixer with three different mixing techniques and the mixing quality of prepared powders is assessed. A significant reduction of mixing time, i.e., more than 50%, is achieved through a novel barrel mixer as compared to a conventional V-blender. Two important properties, hardness and compressive strength of fabricated Al-MMC, are experimentally investigated. At the same time effect of the mixing technique is also studied, and it is evident that hardness and compressive strength improved when powders are mixed using a barrel mixer. Thus, a novel approach to powder mixing has been achieved. An increase in SiC proportion by 5% resulted in an increase in hardness by 14%. The average compressive strength of Al-MMC is highest when reinforcement content is 25%. Due to the uniform dispersion of particles achieved through barrel mixer, compressive strength of MMC is 8–20% higher than the strength of those MMC for which powders are mixed through conventional V-blender. A similar effect is observed in the hardness also, where the average hardness of MMC is 10–20% higher, for which powders are mixed through barrel mixer. Hence, the newly designed barrel mixer provides an effective solution for the quality mixing of powders through the powder metallurgy process for fabricating Al-MMC.