Aluminum and vacancies inα-iron: Dissolution, diffusion, and clustering

First-principle calculations have been performed to study the electronic structure and energetics of the dissolution of aluminum in α-iron and the interaction between Al atoms and vacancies $(V)$. We find that the formation of small VₙAlₘ complexes ($n,m=0--4$) is energetically favorable. Their stability is mainly driven by strong Al-V attractions whereas Al-Al interactions are repulsive. Using ab initio predictions, a rate theory based model that accounts for the evolution of aluminum and vacancies created upon rapid quenching has been developed to explore the influence of Al in the presence of the VₙAlₘ complexes in α-iron. Finally, using the Le Claire's diffusion model, the diffusion properties of solute Al are investigated.