Study of precipitation in Al-Mg-Si Alloys by atom probe tomography II. Influence of Cu additions

作者：Zandbergen M W^*; Cerezo A; Smith G D W

来源：Acta Materialia, 2015, 101: 149-158.

DOI：10.1016/j.actamat.2015.08.018

• Aluminium alloys
• Cu additions
• Age hardening
• Atom probe tomography (APT)
• Precipitation kinetics

Atom probe tomography (APT) analysis and hardness measurements have been used to characterise the early stages of precipitation in three Al-Mg-Si alloys with different Cu contents (Al-0.51 at.%Mg-0.94 at. %Si, with 0.01 at.%, 0.06 at.%, or 0.34 at.% Cu). A range of single and multi- stage heat treatments were chosen to evaluate the changes in precipitation processes. Three ageing temperatures were investigated, 298 K (natural ageing), 353 K (pre-ageing) and 453 K (automotive paint-bake conditions). The Cu content had significant effects on the microstructural evolution within the alloy. Formation of clusters which can act as precursors of elongated precipitates during paint-baking was found to be enhanced with increasing Cu content. This improved the paint-bake hardening response and mitigated the deleterious effects of natural ageing. Cu was present in all precipitates in the highest Cu-containing alloy. These precipitates were believed to be precursors to the Q' phase. Mechanisms for the effects of Cu on precipitation kinetics are proposed.

• 出版日期2015-12