The Evolution of Microstructure and Mechanical Properties of Al-Mn-Fe-Si Alloys During Isothermal Annealing

Recrystallization during isothermal annealing is studied in a twin-roll cast Al-Mn-Fe-Si alloy with Zr addition. Al₃Zr precipitates, which are known to improve the recrystallization resistance by exerting the Zener drag on migrating grain boundaries, form during heat treatment at 450°C. Materials with and without Al₃Zr precipitates are subjected to 4 passes of equal channel angular pressing at room temperature and a submicrometric grain size is achieved. In the course of isothermal annealing materials recrystallize at 400°C, 425°C and 450°C. The time required for recrystallization follows an Arrhenius equation. Recrystallization kinetics is similar independently of the presence of Al₃Zr precipitates. Precipitation of α-Al(Mn,Fe)Si particles is thought to increase the recrystallization resistance in the material without Al₃Zr.