Investigation of microstructure and mechanical properties of Al6061-nanocomposite fabricated by stir casting

In comparison to unreinforced alloy, Al6061 reinforced with hard particles possesses higher strength, stiffness, and wear and creep resistance in a wide temperature range. They can be used for automotive components and aircraft structures. The aim of the present work is to investigate the effects of adding nano-alumina particles to Al6061 alloy and extrusion process on the mechanical and microstructure properties of the composites. For this purpose, Al6061/nano Al2O3 composites were fabricated by stir casting process through injection of Al2O3 particles into the molten Al alloy by argon gas along with stirring using a mechanical stirrer. The nanocomposites were then extruded at 550 °C. The microstructure results revealed that injection of powders in the form of Al/Al2O3 and application of extrusion process led to fabrication of nanocomposites with reasonable distribution of Al2O3 in the matrix alloy with low agglomeration and low porosity. In addition, the extruded samples showed strength and ductility values superior to those of the as-cast samples. It was also found that for both as-cast and extruded samples, with increasing amount of Al2O3 nanoparticles, yield strength and tensile strength increased but elongation decreased.