Density functional theory calculations of solid state-assisted diffusion and positron lifetime in Al-Mg models

Abstract Vacancies within the metallic structure mediate the reconstruction process carried out by solute diffusion, that ultimately nucleate hardening clusters, in a process known as natural aging (NA). Meanwhile, positrons annihilation lifetime spectroscopy (PALS) characterizes the electronic density surrounding a certain bulk defect, by the lifetime period of the elemental particle within certain defective traps. Combining two different approaches, based on density functional theory, it is possible to capture, on the first hand, a modified diffusive behavior including a second non−diffusive impurity into the frequency scheme, upgrading the result from the diffusive impurity solely as well as the self−diffusion character of aluminum. And, on the other hand, by means of realistic positron annihilation signals, fully ab − initio determined, the early stages of NA could be track by systematically enlarged vacancy and magnesium-vacancy clusters within the aluminum matrix, in agreement with previously reported measurements. Graphical Abstract