Examining the effect of the aging state on strength and plasticity of wrought aluminum alloys

A general rule of strength and plasticity is proposed for three typical wrought Al alloys (2xxx, 6xxx, and 7xxx) subjected to different aging times. Investigations of the work-hardening processes and dislocation configurations in tensile and compressive testing reveal that this general rule arises because there is a common mechanism for these three kinds of wrought alloys whereby the tendency for cross-slip increases monotonously with aging time. By analyzing the strain hardening exponent and the stacking fault energy, it is demonstrated that the change in the dislocation slip mode is attributed mainly to the formation of second phases rather than to the matrix composition. Accordingly, a new work-hardening model is proposed for wrought Al alloys containing second phases and this explains the interaction between dislocations and second phases and other relevant experimental phenomena. This study is therefore beneficial for quantitatively investigating and optimizing the strength and plasticity of wrought aluminum alloys.