Influence of two-stage ageing process and Cu additions on conductive Al alloys based on AA 6063

In order to search for an economic process to produce conductive Al alloys, Al-Mg-Si-Cu alloys with different Cu-content based on AA 6063 were explored by applying a two-stage aging method. The formation of cluster (2) at high pre-aging temperature with a large volume fraction, can suppress the negative effect of cluster (1) on the bake-hardening. A proper two-step ageing process was selected as pre-aged at 363 K for 4 h followed by isothermal ageing at 453 K. The Cu addition increases the quantity of solute atoms which also increase the electrical resistivity, and a proper content with Al-0.8Mg-0.58Si-0.6Cu (wt%) can prolong the existence of meta-stable phase, which will guarantee the stability of elevated mechanical and electrical properties simultaneously. Furthermore, extra spots in SADPs caused by Cu addition indicate the close relationship between the structure of clusters/GP zones and the evolution of age-hardening phases.