Structure Evolution and Mechanical Properties of Sheet Al–Cu–Mn–Ca Non-Heat Treatable Alloys

The effect of Ca addition (up to ~3.5 wt.%) on the structure, phase composition, deformability and mechanical properties of hot and cold rolled aluminum alloys containing 5–6%Cu and ~2%Mn alloys has been studied using calculation and experimental techniques. It has been shown that the main structural component of the most promising (wt.%) Al–6Cu–1Ca–2Mn alloy is the eutectic (Al)+Al27Ca3Cu7, which has a fine structure and contains (wt.%) ~5.8 Cu, ~1.6 Ca and ~2 Mn. Increasing the Ca content to more than 1 % leads to a decrease in the alloy processability due to the formation of primary crystals of the Al27Ca3Cu7 phase. It has been shown that combining the eutectic phase Al27Ca3Cu7 crystals in an amount of ~8% and Al20Cu2Mn3 phase dispersoids in the Al–6%Cu–1%Ca–2%Mn alloy delivers a significant increase in the strength of the cold-rolled sheets annealed at 400°C (UTS 319 MPa, YS 269 MPa and δ 8.4 %). Based on the data obtained, the Al–6%Cu–2%Mn–1%Ca composition offers the best combination of deformation processability and mechanical properties. Therefore, it can be considered as a basis for developing new generation heat-resistant wrought aluminum alloys.