Achieving homogeneity in a two-phase Cu-Ag composite during high-pressure torsion

A Cu-8 wt%Ag alloy was processed at room temperature either by high-pressure torsion (HPT) or using a two-step deformation mode of equal-channel angular pressing (ECAP) and HPT. After HPT deformation, different flow patterns were observed on the disk surface without any post-deformation treatment thereby indicating an inhomogeneous shearing deformation. The microhardness distributions throughout the disks were compared after the two different processing routes. It is shown that the microhardness remains very low near the center of the disk although saturated in the outer regions after 10 revolutions. By contrast, an intrinsically homogeneous microhardness may be attained throughout the disk after the two-step deformation of ECAP and HPT. This study suggests a convenient procedure for achieving full homogeneity in high-strength materials during HPT processing.