Effects of stacking fault energy on the thermal stability and mechanical properties of nanostructured Cu–Al alloys during thermal annealing

Effects of stacking fault energy (SFE) on the thermal stability and mechanical properties of nanostructured (NS) Cu-Al alloys during thermal annealing were investigated in this study. Compared with NS Cu-5at.%Al alloy with the higher SFE, NS Cu-8at.%Al alloy exhibits the lower critical temperatures for the initiation of recrystallization and the transition from recovery-dominated to recrystallization-dominated process, which significantly signals its low thermal stability. This may be attributed to the large microstructural heterogeneities resulting from severe plastic deformation. With increasing the annealing temperatures, both Cu-Al alloys present the similar trend of decreased strength and improved ductility. Meanwhile, the remarkable enhancement of uniform elongation is achieved when the volume fraction of Static recrystallization (SRX) grains exceeds -80%. Moreover, the better strength-ductility combination was achieved in the Cu-8at.%Al alloy with lower SFE.