A dilatometric and high-temperature X-ray diffraction study of cold deformation effect on the interaction between precipitation, recovery and recrystallization reactions in Al–12 wt.% Mg alloy

The effect of cold deformation on the interaction between precipitation, recovery and recrystallization reactions in an Al–12 wt.% Mg alloy was studied by dilatometry and high-temperature X-ray diffraction. During continuous heating of cold deformed samples, the dilatometric curves present new dilatometric anomalies which change with increasing prior-deformation. The new dilatometric anomalies were identified by using in situ high-temperature X-ray diffraction and were ascribed to the precipitation/recovery or dissolution/recrystallization interactions. It is established that after small deformations, recovery occurs before as well as during precipitation. However, at high prior-deformation, because of the high density of dislocations, precipitation becomes faster and competes with recovery. In both cases, the effect of recovery is not important in beginning of the process due to the interaction between dislocations and Mg atoms and it becomes more important after the reduction of Mg content and when the precipitates are coarsened and their interparticle spacing is increased. The formation of a new texture during recrystallization process can produce an increasing of the thermal expansion coefficient.