Comparative analysis of the effect of magnesium and zinc on the structure and mechanical properties of hot-rolled and cold-rolled alloy Al–2%Cu–1.5%Mn sheets

In this study, using an example of cold-rolled sheets, the separate effect of magnesium and zinc in an amount up to 2% upon the structure and mechanical properties of a thermally non-hardening heat-resistant alloy Al–2%Cu–1.5%Mn, the composition of which is optimized to obtain the maximum fraction of Al₂₀Cu₂Mn₃ phase, is studied. It is found that in a cast state, zinc is completely contained within aluminum solid solution, and magnesium is partially included within eutectic particles of the Al₂CuMg phase. These elements hardly affect the amount of Al₂₀Cu₂Mn₃ phase, which is formed during deformation and heat treatment in the form of nanoscale dispersoids. It is found that addition of 1% magnesium increases the strength of cold-rolled sheets of the base alloy by 15% after 3‑hour annealing at 400 °C, without reducing the ductility. In turn, alloying with zinc does not have a significant effect on strength.