Effect of tool diameter ratio on the microstructural characteristics of a solid-state processed aluminum based metal matrix composite

Abstract

Stir cast aluminum based metal matrix composites (MMCs) with silicon carbide (SiC) reinforcement particles consist of cast product dendrites and large agglomerated reinforcements. The agglomeration of SiC particles creates a difference in properties in the composite system. Friction stir processing (FSP) is used to overcome the uneven distribution of SiC particles in the aluminum matrix. The friction stir processed (FSPed) microstructure is significantly influenced by the process parameters used for processing. In FSP, the effect of the tool diameter ratio (tool shoulder diameter to pin diameter) on material flow, material mixing, material consolidation is more predominant than other parameters. Hence, a perfect combination of shoulder diameter to pin diameter is required to produce sufficient material flow. In this investigation, the tool diameter ratio is varied from 2.0 to 4.0 for processing composite material and thus FSPed zones were subjected to micro structural characterization. It was concluded that a tool diameter ratio of 3.0 yielded a defect free stir zone with higher hardness compared to other ratios.