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).