Dynamic recrystallization and precipitation in an Al–Mg–Sc alloy: effect of strain rate

Al–Mg–Sc alloy ingots were compressed 80% at different strain rates (1/s, 0.01/s and 0.0001/s) and different temperatures (300 °C and 450 °C). The microstructure was characterized by SEM, EBSD, XRD and TEM. The EBSD results show that the samples with a deformation rate of 0.01/s have the largest number of tiny equiaxed grains at the grain boundaries, but the equiaxed grains in the 0.0001/s sample are less and larger. This indicates that the number of new equiaxed grains does not always increase with decreasing strain rate. Furthermore, the TEM results confirmed that the recrystallization mechanism with a strain rate of 0.0001/s is similar to in situ recrystallization. The XRD results show that with the increase of temperature and the decrease of strain rate, there are fewer dislocations in the samples after thermal deformation. The particle stimulated recrystallization is also different in the 0.01/s sample and the 0.0001/s sample. Furthermore, at a strain rate of 0.0001/s, a large number of fine Al3(Sc,Zr) particles appear, which is due to the dynamic precipitation during slow thermal deformation.