Use of thermodynamic calculation to predict the effect of Si on the ageing behavior of Al–Mg–Si–Cu alloys

Thermodynamic calculation was employed to predict the influence of Si content on the ageing behavior of Al–Mg–Si–Cu alloys. In addition, experiments were carried out to verify the predictions. The results show that thermodynamic calculation can predict the effect of Si content on the ageing behavior of the studied alloys. This study further proposes that the hardness level of alloys during ageing is directly related to the Si content in the as-quenched supersaturated solution, while the precipitation strengthening effect is directly related to the Mg2Si level of the alloys.

Research highlights
► Thermodynamic calculation can predict the ageing behavior of 6xxx alloys.
► The hardness level of the alloys depends on the Si content in as-quenched matrix.
► The precipitation strengthening effect depends on the Mg2Si level of the alloys.