Influences of applied electric field applying during aging process on δ′ phase (Al₃Li) precipitation and activation energy of its dissolution

Influences of applied electric field during aging process on δ′ phase (Al₃Li) precipitation and activation energy of its dissolution in 1420 alloy were studied by TEM and DSC techniques. It was found that the electric field increased average particle size of δ′ phase in aged 1420 alloy. Kinetics of δ′ phase dissolution was calculated by adopting mechanism function of the first order reaction, F1: f(α) = 1-α, and that of three dimension diffusion, D3: f(α) = 1.5 × (1-α)^2/3 × [1- (1-α)^1/3]^-1, respectively. The results showed that D3 was the most probably mechanism function of δ′ phase dissolution, and the electric field reduced apparent activation energies of δ′ phase dissolution during thermal analysis process. By analysis, it was found that electric field increased the driving force of δ′ phase particles dissolution, and thereby decreased the apparent activation energy of their dissolution by promoting growth and coarseness of δ′ phase during aging process.