Liu Shuai, Liao Binbin, Nie Baohua, Fan Touwen, Chen Dongchu, Zhang Jianglong, Song Yu
School of Materials Science and Hydrogen Energy, Foshan University, Foshan 528000, China.
Research Institute of Automobile Parts Technology, Hunan Institute of Technology, Hengyang 421002, China.
Molecules. 2023 Sep 21;28(18):6727. doi: 10.3390/molecules28186727.
Atomic diffusion by the vacancy defect of L1-AlM (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 (V) were, respectively, the preferred diffusion paths in AlM 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-V) was AlZr < AlY < AlEr < AlSc. The AlSc phase had high stability with a high self-diffusion activation barrier, while the AlZr and AlY phases were relatively unstable with a low self-diffusion activation energy. Moreover, the atomic-diffusion behavior between the core and shell layers of L1-AlM was also further investigated. Zr atoms were prone to diffusion into the AlY core layer, resulting in no stable core-shelled Al(Y,Zr), which well agreed with experimental observation.
基于第一性原理计算，研究了L1-AlM（M = Sc、Zr、Er、Y）中空位缺陷引起的原子扩散。首先评估了点缺陷形成能。然后，通过爬山图像推挤弹性带（CI-NEB）方法获得了不同扩散路径的迁移能。结果表明，在富铝和富M条件下，Al原子和M原子通过由Al空位（V）介导的最近邻跳跃（NNJ）扩散分别是AlM相中的优先扩散路径。其他机制，如六跳循环（6JC）和次近邻跳跃（NNNJ），在能量上受到抑制。NNJ（Al-V）的激活势垒顺序为AlZr < AlY < AlEr < AlSc。AlSc相具有高稳定性和高自扩散激活势垒，而AlZr和AlY相相对不稳定，具有低自扩散激活能。此外，还进一步研究了L1-AlM核层和壳层之间的原子扩散行为。Zr原子易于扩散到AlY核层中，导致没有稳定的核壳结构Al(Y,Zr)，这与实验观察结果吻合良好。
