Effects of Si and Ag additions on ageing behaviour and microstructure evolution of Al-Cu-Mg alloy

The effects of trace additions of Si and Ag on the ageing behaviour and microstructure evolution of low Cu/Mg ratio Al-Cu-Mg alloy were investigated by using analytical transmission electron microscopy and Monte Carlo simulation. The results indicate that the age hardening response can be enhanced by the trace Si addition as well as Ag. The Monte Carlo simulation results show that the addition of Si results in a refinement of Mg clusters and Cu-Mg clusters, and the addition of Ag promotes the formation of lots of Mg-Ag clusters. Trace Si and Ag additions significantly alter the clustering process during early stages of ageing, resulting in different microstructural evolution processes during subsequent aging process.