标题： 基于第一性原理的晶界对氟诱导镍铬合金初始腐蚀影响的研究 显示英文标题

标题： First-Principles Investigation of Grain Boundary Effects on Fluorine-Induced Initial Corrosion of NiCr Alloys

摘要： 由于选择性攻击导致晶界（GBs）处的铬耗尽，是镍铬合金熔盐腐蚀中的一个关键问题。 尽管从众多实验研究中可以看出GBs在这一过程中的重要性，但大多数理论工作主要集中在氟与理想晶体表面的相互作用上，忽略了GB局部环境的复杂性。 本研究旨在通过采用密度泛函理论（DFT）来研究熔融氟化盐环境中NiCr合金中GB处的原子相互作用和铬溶解机制。 具体而言，构建了一个$\Sigma$5(210)/(001)对称倾斜GB，以探索氟在Ni(100)和铬掺杂的Ni(100)表面上的吸附能。 我们发现，氟在GB位点表现出强烈的结合偏好，而铬掺杂则增强了这种效应，与体相Ni表面相比，吸附能更高。 氟与铬的结合显著改变了Cr-F复合物与Ni基底之间的相互作用以及铬原子的溶解势垒；CrF$_3$的形成大大降低了铬溶解的能量势垒。 这项工作突出了GBs在增强氟吸附和加速铬耗尽中的关键作用，为镍铬合金早期腐蚀机制提供了新的见解。 显示英文摘要

摘要： Chromium depletion at grain boundaries (GBs) due to selective attack is a critical issue in the molten salt corrosion of NiCr alloys. Despite the importance of GBs in this process from numerous experimental studies, most theoretical work has predominantly focused on fluorine interactions with idealized crystalline surfaces, neglecting the complexity of GB local environments. This study aims to bridge that gap by employing density functional theory (DFT) to investigate the atomic interactions and Cr dissolution mechanisms at GB in NiCr alloys under molten fluoride salt environments. Specifically, a $\Sigma$5(210)/(001) symmetrical tilt GB is constructed to explore the adsorption energies of fluorine on Ni(100) and Cr-doped Ni(100) surfaces. We find that fluorine exhibits a strong preference for binding at GB sites, with Cr doping amplifying this effect, leading to higher adsorption energies compared to bulk Ni surfaces. Fluorine bonding with Cr significantly alters the interaction between Cr-F complexes and Ni substrate, and the consequent dissolution barriers for Cr atoms; the formation of CrF$_3$ largely reduces the energy barrier for Cr dissolution. This work highlights the essential role of GBs in enhancing fluorine adsorption and accelerating Cr depletion, providing new insights into the mechanisms of early-stage corrosion in NiCr alloys.