Quantitative characterization of aging precipitation behavior and strengthening mechanisms of Al–Li alloy under pre-deformation

The synergistic effect of pre-deformation (0–10 %) on the aging precipitation behavior, microstructure evolution and strengthening mechanisms of 2195 Al–Li alloy. Results demonstrate that pre-deformation significantly enhances aging kinetics, reducing the peak-aging time from 30 h (0 % pre-deformation) to 18 h (10 % pre-deformation). The optimal pre-deformation level of 4 % yielded a superior combination of yield strength (525.01 MPa), ultimate tensile strength (550.57 MPa), and elongation (10.01 %). Compared to the non-deformed alloy, the pre-deformed (4 %) alloy exhibited a significant increase in dislocation density from 1.45 × 10¹⁴ m⁻² to 5.12 × 10¹⁴ m⁻². This enhanced dislocation density promoted the nucleation of considerably finer T₁ precipitates, reducing their average diameter from 136.54 nm to 65.59 nm, while simultaneously suppressing the formation of the θ′ phase. Pre-deformation effectively lowered the activation energy required for T₁ precipitation from 159.78 kJ/mol to 153.40 kJ/mol, which led to an acceleration in nucleation kinetics. Quantitative strengthening mechanisms analysis indicated precipitation strengthening (234.8 MPa) as the dominant contributor in pre-deformed alloys. The study provides a ageing precipitation kinetics framework for optimizing pre-deformation parameters to achieve synergistic strength-ductility improvements in Al–Li alloys.