Optimizing microstructure and mechanical properties of 2195 Al–Li alloy via thermomechanical treatment: Precipitate regulation mechanism

The mechanical properties of the third-generation 2195 Al-Cu-Li alloy are critically governed by thermomechanical treatment (TMT)-mediated precipitate regulation. Optimized solution treatment (530 °C for 60 minutes followed by water quenching) achieves complete dissolution of the residual Al 2 Cu phases, forming a supersaturated solid solution with peak hardness (121 HV) and tensile strength (453 MPa). Water quenching enhances the strength by 12.5% compared to air cooling, by suppressing the GP zone formation. For T8 ageing, 7–9% pre-deformation promoted homogeneous T 1 (Al 2 CuLi) precipitation while inhibiting θ′ (Al 2 Cu), yielding an optimal balance of strength and ductility (637 MPa UTS, 586 MPa YS and 8.7% EL) after 48–72 hours at 145 °C. For T3 ageing, 5% pre-deformation enhances δ′ (Al 3 Li) nucleation via lattice distortion. However, excessive deformation reduces ductility and natural ageing for 30 days stabilizes δ′ precipitation, providing limited strengthening. Fractography transitions from ductile dimple to brittle intergranular modes with increasing pre-deformation or ageing temperature. This establishes a quantitative TMT-precipitate-property relationship that can be used to guide aerospace applications.