Three-dimensional representations of hardness distributions after processing by high-pressure torsion

The Vickers microhardness was recorded on the polished surfaces of disks of pure aluminum and an Al-6061 alloy after processing by high-pressure torsion. The results are shown in three-dimensional representations that reveal clearly the gradual evolution towards a homogeneous structure. This evolution is reasonably rapid in pure Al but it is slower in the alloy due to the lower rate of recovery. The results show evolution is assisted by increasing the numbers of turns and/or the imposed pressure. The results reveal significant differences between pure Al and the Al-6061 alloy which are consistent with earlier results obtained during processing by equal-channel angular pressing. (C) 2008 Elsevier B.V. All rights reserved.