Annealing-Induced Structural–Phase Transformations in an Al–Zn–Mg–Fe–Ni Alloy after High Pressure Torsion

Abstract—The evolution of the microstructure and phase composition of the eutectic Al–Zn–Mg–Fe–Ni alloy subjected to severe plastic deformation by high pressure torsion has been investigated during annealing. The deformation treatment has resulted in a composite with a nanostructured matrix, namely, an Al solid solution alloyed with zinc and magnesium, and comprising submicron Al9FeNi aluminides. The sequence and the kinetics of post-deformation processes (recovery, aging, recrystallization) during the heating of the alloy to 400°C have been established. Heating to 200°C has been shown to preserve the nanostructural state and the high hardness (1100 MPa) of the alloy due to recovery and aging processes taking place simultaneously. The tendency to recrystallization increases with increasing temperature; and static recrystallization becomes the main relaxation process accompanied by grain growth (to 30 µm) and a decrease in hardness.