Molecules (Sep 2023)

First-Principles Study of Atomic Diffusion by Vacancy Defect of the L1<sub>2</sub>-Al<sub>3</sub>M (M = Sc, Zr, Er, Y) Phase

  • Shuai Liu,
  • Binbin Liao,
  • Baohua Nie,
  • Touwen Fan,
  • Dongchu Chen,
  • Jianglong Zhang,
  • Yu Song

DOI
https://doi.org/10.3390/molecules28186727
Journal volume & issue
Vol. 28, no. 18
p. 6727

Abstract

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Atomic diffusion by the vacancy defect of L12-Al3M (M = Sc, Zr, Er, Y) was investigated based on a first-principles calculation. The point defect formation energies were firstly evaluated. Then, the migration energy for different diffusion paths was obtained by the climbing-image nudged elastic band (CI-NEB) method. The results showed that Al atomic and M atomic diffusions through nearest-neighbor jump (NNJ) mediated by Al vacancy (VAl) were, respectively, the preferred diffusion paths in Al3M phases under both Al-rich and M-rich conditions. The other mechanisms, such as six-jump cycle (6JC) and next-nearest-neighbor jump (NNNJ), were energetically inhibited. The order of activation barriers for NNJ(Al-VAl) was Al3Zr 3Y 3Er 3Sc. The Al3Sc phase had high stability with a high self-diffusion activation barrier, while the Al3Zr and Al3Y phases were relatively unstable with a low self-diffusion activation energy. Moreover, the atomic-diffusion behavior between the core and shell layers of L12-Al3M was also further investigated. Zr atoms were prone to diffusion into the Al3Y core layer, resulting in no stable core-shelled Al3(Y,Zr), which well agreed with experimental observation.

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