Micro-Indentation of Aluminum Processed by Equal Channel Angular Extrusion

The near-surface deformation of equal-channel angular extruded (ECAE) pure aluminum was investigated using the micro-indentation technique. Compared with fully annealed Al samples, there is a distinguishable difference in the indentation deformation. The unloading slope of the ECAE deformed Al after a short unloading period was found to be less than that of the annealed samples due to plastic recovery. Work hardening was observed, which depended on the history of local deformation. A new relationship between the plastic energy dissipated in the indentation and the applied load was derived, which is supported by the experimental results.