The effect of cold deformation on the kinetics of the β precipitates in an Al-Mg-Si alloy

Kinetics of beta precipitation in an Al-0.55 pct Mg-1.1 wt pct Si (AA6022) in both deformed and undeformed conditions were investigated by means of differential scanning calorimetry (DSC). Transmission electron microscopy (TEM) analysis on predeformed samples was also performed to study the effect of deformation on beta precipitates. It was found that the introduction of dislocations changes the precipitate type from beta to beta' and Q'. Also the measured activation energy for precipitate formation in the case of predeformed and undeformed samples was compared. The results show that dislocations facilitate precipitation by decreasing the activation energy.