High strength Al–Al2O3p composites: Optimization of extrusion parameters

Composite aluminium alloys reinforced with Al2O3p particles have been produced by squeeze casting followed by hot extrusion and a precipitation hardening treatment. Good mechanical properties can be achieved, and in this paper we describe an optimization of the key processing parameters. The parameters investigated are the extrusion temperature, the extrusion rate and the extrusion ratio. The materials chosen are AA 2024 and AA 6061, each reinforced with 30 vol.% Al2O3 particles of diameter typically in the range from 0.15 to 0.3 μm. The extruded composites have been evaluated based on an investigation of their mechanical properties and microstructure, as well as on the surface quality of the extruded samples. The evaluation shows that material with good strength, though with limited ductility, can be reliably obtained using a production route of squeeze casting, followed by hot extrusion and a precipitation hardening treatment. For the extrusion step optimized processing parameters have been determined as: (i) extrusion temperature = 500 °C–560 °C; (ii) extrusion rate = 5 mm/s; (iii) extrusion ratio = 10:1.