AI 中文总结
研究镍铬合金在熔融FLiNaK中腐蚀诱导晶界迁移的原子机制，用反应分子动力学研究四个代表性晶界及体表面腐蚀，发现表面晶体学和晶界特征对腐蚀的影响，识别出腐蚀驱动的晶界迁移机制，指出低能特殊边界是晶界工程目标。
AI 中文摘要
镍铬结构合金在熔融氟化物盐中的腐蚀是一个持续存在的材料降解问题，然而晶界在此过程中的原子作用仍知之甚少。本文利用反应分子动力学研究了镍铬合金在熔融FLiNaK中通过四个代表性晶界（Σ3(111)、Σ11(113)、Σ5(012)和Σ5(013)）以及相应体表面的腐蚀情况。表面晶体学控制初始溶解阶段，而晶界特征决定腐蚀的空间定位和较长时间演化。还识别出一种腐蚀驱动的晶界迁移机制，氟的定位、优先铬溶解和空位介导的迁移共同驱动界面远离脱合金区域运动。连贯的Σ3(111)边界抑制这些过程，表明低能特殊边界是耐腐蚀镍铬合金晶界工程的目标。
英文摘要
Corrosion of Ni-Cr structural alloys in molten fluoride salts is a persistent material degradation problem, yet the atomistic role of grain boundaries in this process remains poorly understood. Here we use reactive molecular dynamics to investigate corrosion of NiCr alloys in molten FLiNaK across four representative grain boundaries ($\Sigma3(111)$, $\Sigma11(113)$, $\Sigma5(012)$, and $\Sigma5(013)$) and corresponding bulk surfaces. Surface crystallography controls the initial dissolution stage, while grain boundary character governs the spatial localization and longer-time evolution of corrosion. We further identify a corrosion-driven grain boundary migration mechanism in which fluorine localization, preferential chromium dissolution, and vacancy-mediated mobility together drive interfacial motion away from the dealloyed region. The coherent $\Sigma3(111)$ boundary suppresses these processes, indicating low-energy special boundaries as targets for grain boundary engineering of corrosion-resistant Ni-Cr alloys.
Comments22 pages, 6 figures
