effects of rheocasting and heat treatment on microstructure characteristics and mechanical properties of high performance 2024 aluminium alloy

The effects of the rheocasting process and T6 heat treatment on microstructure and mechanical properties of 2024 aluminium alloy were investigated. The results show that the temperature range for the solid–liquid state was roughly between 591◦C and 652◦C, and the finer microstructure in rheocasting in comparison with the one in conventional casting was attributed to more fragmentation in dendrite arms and consequently reduction in size of primary particles (38-45μm), especially for specimens which were fabricated of around 600-820 rpm. It was proved that rheocasting specimens have improved mechanical properties over the conventional casting ones. Furthermore, the results show that standard solution time for conventional wrought alloy 2024 (2 h at 500◦C) gave incomplete homogenization of rheocasted material. Longer times (4h) at 500◦C are required for complete solutionisation of Al2Cu,and the T6 heat treatment can strengthen AA2024 alloy, while the compressibility is reduced at the same time. Low hardness values in the as-rheocasted 2024aluminium alloy were increased by subsequent heat treatment

Keywords:

AA2024 alloy , Rheocasting , Mechanical stirring , Microstructure , T6 heat treatment