Effect of solid solution treatment on the kinetics of hydrogen porosity evolution and mechanical properties in Al–Cu–Li alloys

The evolution kinetics of hydrogen porosity during solid solution treatment (SST) of vacuum-cast Al–Cu–Li alloys and the effect of porosity defects on the mechanical properties of the alloys were investigated. It has shown that porosity at 6hrs SST was dominated by nucleation and has a linear correlation with time, APS = (0.05 ± 0.06)＋(0.11 ± 0.01) t. However, the growth of porosity at 12 h is evidenced by a decrease in the number of pores and an increase in the size of large pores, increasing inter-porosity clustering due to Ostwald ripening. 3D Quasi-in situ XCT showed that the hydrogen concentration at the interface in the early stages of the solid solution was not adequate to balance the surface tension of porosities with an equivalent diameter of less than 23.2 μm and that the presence of vacancies created by unbalanced cross-diffusion provided favorable sites for porosity nucleation, reducing the energy required for porosity nucleation. The effect of effective porosity in the cross-section on the tensile strength satisfies lnσ-lnσ0 = αlnfp. In addition, simulations coupled with multi-scale simulations of hydrogen diffusion were performed to verify this conclusion.