Molecular dynamics studies of sluggish grain boundary diffusion in equiatomic FeNiCrCoCu high-entropy alloy
Molecular dynamics studies of sluggish grain boundary diffusion in equiatomic FeNiCrCoCu high-entropy alloy
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DOI：
10.1007/s10853-023-08568-3
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发表时间：
2023-05
影响因子：
4.5
通讯作者：
Axel Seoane;D. Farkas;X. Bai
中科院分区：
文献类型：
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作者：
Axel Seoane;D. Farkas;X. Bai
通过分子动力学模拟研究等原子 FeNiCrCoCu 高熵合金 (HEA) 模型中沿 a < 100 > Σ5(210) 对称倾斜晶界的自扩散过程，方向垂直于和平行于倾斜轴。为了进行比较，还对 HEA 的每种纯组分的晶界扩散过程进行了量化。最重要的是，将结果与使用相应“平均原子”势沿相同晶界的扩散进行比较，该势具有类似的平均体积特性，但没有 HEA 中的成分随机性。这些比较表明，HEA 晶界中的自扩散比平均原子材料以及纯组分的平均自扩散慢，这表明 HEA 中这种特殊晶界存在“缓慢”扩散效应。这种效应在低温下很显着，但在较高温度下减弱，表明晶界缓慢扩散可能与温度有关。有趣的是，晶界缓慢扩散行为与之前使用相同方法和原子间势研究的体扩散不同，在体扩散中没有观察到显着的缓慢扩散效应。我们的进一步分析表明，HEA 中成分复杂性产生的“捕获效应”与该特殊晶界处的受限二维扩散路径相结合，是造成观察到的晶界缓慢扩散的原因。图形摘要
Molecular dynamics simulations are conducted to study the self-diffusion process along a < 100 > Σ5(210) symmetric tilt grain boundary in a model equiatomic FeNiCrCoCu high-entropy alloy (HEA), for the directions both perpendicular and parallel to the tilt axis. For comparison, the grain boundary diffusion process is also quantified for each of the pure components of the HEA. Most importantly, the results are compared with the diffusion along the same grain boundary using the corresponding “average atom” potential that has similar average bulk properties but no compositional randomness as in the HEA. These comparisons show that the self-diffusion in the HEA grain boundary is slower than in the average atom material as well as the average of pure components, suggesting that a “sluggish” diffusion effect exists for this special grain boundary in the HEA. This effect is significant at low temperatures but diminishes at higher temperatures, indicating that the grain boundary sluggish diffusion is likely temperature dependent. Interestingly, the grain boundary sluggish diffusion behavior is different from the bulk diffusion that was studied previously using the same methods and interatomic potentials, in which no significant sluggish diffusion effect was observed. Our further analysis suggests that the combination of the “trapping effect” by compositional complexity in the HEA and the confined 2-D diffusion paths at this special grain boundary is responsible for the observed grain boundary sluggish diffusion.Graphical abstract