Effect of post equal-channel-angular-pressing aging on the modified 7075 Al alloy containing Sc

The effect of post-ECAP low-temperature aging on mechanical properties of the 7075 Al aluminum alloy containing Sc (7 × 51) after a single pressing was examined. The best aging effect on strengthening was achieved at 373 K after 20-30 h. After the post-ECAP aging treatment, the yield stress and UTS of the 7 × 51 alloy have increased to 680 MPa and 730 MPa, respectively. This achievement is remarkable when compared with the 7075 Al alloy conventionally ECAP processed for three passes exhibiting the YS of 667 MPa and UTS of 677 MPa. The post-ECAP aging was also effective in improving the tensile ductility of the ECAPed alloy. The unECAPed and ECAPed 7 × 51 Al alloys before or after aging at 373 K showed a big difference in strain hardening ability. According to the model assessing the extent to which the hardening and softening mechanisms are active during the plastic deformation of the materials, the low strain hardening rate of the ECAPed alloy could be attributed to a significant contribution to softening by cross slip and a small contribution of precipitation to hardening.