Accelerated and enhanced artificial ageing of 2195 Al-Li alloy by electric current

An accelerated artificial ageing process with the enhanced strength of 2195 Al-Li alloy has been reported and systematically characterized under the excitation of electric current in this study. Compared with conventional ageing (CA), electrically-assisted ageing (EAA) reduces the time to reach the equivalent peak strength by 42 %. More importantly, EAA achieves a significantly higher peak yield strength of 439 MPa, substantially exceeding the CA peak of 387 MPa. Through combined in-situ and ex-situ microstructural analyses, the accelerated precipitation kinetics and strength enhancement under EAA are attribute to the enhanced atom diffusion, nucleation and transformation kinetics of precipitates due to current-induced electro migration effect and drift electro scattering effects. Specifically, the more nucleation sites for θ′ phase at the early ageing stage and more fine T₁ phase at the late ageing stage result in higher yield strength under EAA. The results and methods presented here provide a potential way for the further design of fast ageing of Al-Li alloys with electric energy.