Investigations on serrated flow in 8090 Al alloy and 8090 Al-SiCp composites occurring during dynamic ultra low load micro hardness (DUH) indentation

Occurrence of plastic instabilities during depth sensing indentation in 8090 Al alloy and 8090 Al-SiCp composites containing 8 and 15 vol.% of SiC particles have been investigated by dynamic ultra low load micro hardness (DUH) technique. The unreinforced alloy shows instabilities (serrations) in the load-displacement curve in the as-extruded (AE) and solution-treated conditions. However, the magnitude of serrations becomes negligible after ageing. Al-Li-8% SiC composite shows signs of serrations in the solution-treated condition. On the other hand, Al-Li-15% SiC composite shows almost no or negligible serrated flow in all the conditions (as-extruded, solution-treated, and aged).