Mechanical Properties and Microstructure of an Al-Zn-Mg-Sc-Zr Alloy Processed by Warm Equal Channel Angular Pressing and Subsequent Aging

Abstract

An ultrafine-grained Al-Zn-Mg-0.1Sc-0.1Zr alloy was obtained by warm equal channel angular pressing (ECAP) and cold rolling. The microstructure evolution of the alloy during deformation and after subsequent aging was investigated by transmission electron microscopy. The results showed that the alloy grains were remarkably refined and that the dislocation density considerably increased after serve deformation. Tensile tests revealed that the yield strength (YS), ultimate tensile strength (UTS) and elongation of the cold-rolled Al-Zn-Mg-Sc-Zr alloy were ~ 456 MPa, ~ 469 MPa and 16.7%, respectively. After 16 ECAP passes, higher strength (YS: ~ 526 MPa, UTS: ~ 589 MPa) was achieved, with the elongation decreasing to ~ 11.7%. After optimal aging, the YS and UTS of the sample subjected to 16 ECAP passes increased to ~ 594 MPa and ~ 606 MPa, respectively, maintaining an appropriate elongation of ~ 10%. The main strengthening mechanisms and microstructure evolution during ECAP and subsequent aging was discussed.