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

Abstract 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 Al 2 O 3 composites were fabricated by stir casting process through injection of Al 2 O 3 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/Al 2 O 3 and application of extrusion process led to fabrication of nanocomposites with reasonable distribution of Al 2 O 3 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 Al 2 O 3 nanoparticles, yield strength and tensile strength increased but elongation decreased.

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