Quenching Sensitivity of 2195 Aluminum-Copper-Lithium Alloy Studied Using TTP Diagrams and Immersion End-Quenching Experiments

Based on interruption quenching experiments and immersion end-quenching experiments, the time–temperature–property (TTP) curve and hardness curve of the 2195 aluminum-copper-lithium (Al-Cu-Li) alloy were determined. Scanning electron microscopy and (high-resolution) transmission electron microscopy were used to thoroughly study its quenching sensitivity. The experimental findings have demonstrated that the curve TTP of the 2195 Al-Cu-Li alloy features a nose temperature of 365°C, a critical transformation time of 0.33 s, and a quench sensitivity temperature range of 213.1–458.9°C. The end distance increased from 5 mm to 145 mm with a hardness reduction rate of 25.6%. The size and quantity of the quenched precipitation phases θ and T₁ increased at grain boundaries and within grains as the quenching rate dropped. The quenched precipitation phase θ phase precipitated at (sub)grain boundaries and within the recrystallized grains, and the quenched precipitation phase T₁ phase precipitated at subgrain boundaries and in high dislocation density subgrain regions. Numerous Cu and Li solute atoms in the matrix were consumed by the precipitation of numerous quenched precipitation phases at the grain boundaries and within the grains, forming many precipitation-free zones (PFZ), which caused a drastic decrease in the number of nano-age-strengthened T₁ phases and a notable reduction in the alloy hardness.