Microstructure and mechanical characterization of Al6061 based composite and nanocomposites prepared via conventional and ultrasonic-assisted melt-stirring techniques

In the current work, Al6061-based composites (2 wt% SiC) and nanocomposites (2 wt% BN, TiO2, Al2O3, MWCNT and Graphene) were prepared via a conventional melt stirring and ultrasonic-assisted melt-stirring approach. In this study, an effort has been made to reduce the agglomeration and clustering of reinforcing particles in the matrix slurry. Hence, reinforcing particles were pre-processed employing ultrasonic liquid processing (ULP) and ball milling (BM) approach prior to mixing in molten matrix slurry. Further, microstructure and mechanical characterization of the specimens fabricated via conventional melt stirring and ultrasonic-assisted melt-stirring approaches were performed and compared. The microscopic analysis (optical microscopy and scanning electron microscopy), microhardness, tensile strength, flexural strength and fractography were performed to analyze the influence of conventional melt-stirring and ultrasonic-assisted melt-stirring on the resulting properties of the fabricated composite and nanocomposite specimens. Microstructure investigations demonstrated better dispersal of reinforcing particles in the specimens prepared via a combined effort of ultrasonic-assisted melt-stirring and reinforcement pre-processing approach. Also, mechanical properties investigation revealed that the specimens prepared via the ultrasonic-assisted melt-stirring approach have superior strength and hardness over the specimens fabricated via the conventional melt-stirring technique. The ultimate tensile and flexural strength of Al6061-2 wt%BN nanocomposite prepared via ultrasonic-assisted melt-stirring reached 246.01 and 498.03, which was 143.57 % and 116.26 % higher than that of Al6061 specimen prepared via conventional melt-stirring. Al6061-2 wt%MWCNT nanocomposite prepared via ultrasonic-assisted melt-stirring has a maximum microhardness (Vickers’s) of 117.1 HV, which was 74.25 % higher than that of Al6061 prepared via conventional melt-stirring. Moreover, Al6061-2 wt%SiC nanocomposite prepared via ultrasonic-assisted melt-stirring has a maximum (Rockwell) of 89.8 HR, which was 105.02 % higher than that of Al6061 prepared via conventional melt-stirring. [Display omitted]