Effect of aging treatment on microstructure and mechanical properties of a new Al-Li-Cu alloy

Effect of aging treatment on microstructure and mechanical properties of a new type Al-Li-Cu alloy was investigated by using TEM analysis. The results show that the main strengthening phases in the alloy are δ', T₁, θ'/θ″, δ'/β'(Al₃Zr) and T₁/θ' phase. With aging time prolonging, a large amount of 0" and a small amount of θ', δ'/β phases precipitate first, and then the θ″ phase decreases but θ', δ'/β' phases increase for the alloy after aging at 143°C for 35 h. A small amount of θ', T₁/θ' and a large amount of T₁ phases are the main phases in the sample for the alloy aged at 143°C for 37 h. With the aging temperature increasing, a large amount of δ'/β' and a small amount of θ', θ″ phases precipitate first. δ', δ'/β' and θ' phases are the main phases for the alloy aged at 143°C. A small amount of θ', T₁/θ' and a large amount of T₁ phases are the main phases when aged at 148°C. A good combination of the strength and plasticity is obtained for the alloy aged at 143°C for 35 h.