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

Abstract

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.