Effects of solute segregation on surface properties of dilute Al-X (X = Li, Sn) alloys from first-principles calculations

Abstract

Considering the interactions between solute atom (Li or Sn) and various surfaces, along with the ones between solute atoms in the surfaces, this work applies the first-principles method to investigate the influences of solute atoms on the surface energy of dilute Al alloys at room temperature, and further predicts the nano-crack nucleation along different surfaces. The statistical ordered surface configurations are depicted for ensuring the maximum surface concentrations of solute-atom segregations. The Gaussian-Like distribution (GLD) model is introduced to describe the distribution of solute atoms. Results indicate that the nano-crack nucleation may occur along the (1¯10) surface in the region of dilute Li atom less than 0.016%, but along the (1¯11) surface in the region of high concentration exceeding 0.016%. While Sn atom has a fairly stronger effect on reducing the surface energy than Li atom, especially in the (001) surface, suggesting that the nano-cracks are likely to nucleate along (001) surface under the action of Sn atom. This work provides a valuable guidance for theoretical and experimental study of the nano-crack nucleation in Al alloys.