Liu Xiaoyang, Liu Yang, Gibson Luke D, Ge Mingyuan, Olds Daniel, Leshchev Denis, Bai Jianming, Plonka Anna M, Halstenberg Phillip, Zhong Hui, Ghose Sanjit, Lin Cheng-Hung, Zheng Xiaoyin, Xiao Xianghui, Lee Wah-Keat, Dai Sheng, Samolyuk German D, Bryantsev Vyacheslav S, Frenkel Anatoly I, Chen-Wiegart Yu-Chen Karen
Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NY, USA.
Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
Phys Chem Chem Phys. 2024 Aug 14;26(32):21342-21356. doi: 10.1039/d4cp01122h.
Molten salts play an important role in various energy-related applications such as high-temperature heat transfer fluids and reaction media. However, the extreme molten salt environment causes the degradation of materials, raising safety and sustainability challenges. A fundamental understanding of material-molten salt interfacial evolution is needed. This work studies the transformation of metallic Cr in molten 50/50 mol% KCl-MgCl multi-modal synchrotron X-ray nano-tomography, diffraction and spectroscopy combined with density functional theory (DFT) and molecular dynamics (AIMD) simulations. Notably, in addition to the dissolution of Cr in the molten salt to form porous structures, a δ-A15 Cr phase was found to gradually form as a result of the metal-salt interaction. This phase change of Cr is associated with a change in the coordination environment of Cr at the interface. DFT and AIMD simulations provide a basis for understanding the enhanced stability of δ-A15 Cr bcc Cr, by revealing their competitive phase thermodynamics at elevated temperatures and probing the interfacial behavior of the molten salt at relevant facets. This study provides critical insights into the morphological and chemical evolution of metal-molten salt interfaces. The combination of multimodal synchrotron analysis and atomic simulation also offers an opportunity to explore a broader range of systems critical to energy applications.
熔盐在各种与能源相关的应用中发挥着重要作用，例如作为高温传热流体和反应介质。然而，极端的熔盐环境会导致材料降解，带来安全和可持续性挑战。因此需要对材料 - 熔盐界面演化有基本的了解。这项工作通过多模态同步加速器X射线纳米断层扫描、衍射和光谱技术，并结合密度泛函理论（DFT）和分子动力学（AIMD）模拟，研究了金属Cr在50/50摩尔% KCl - MgCl熔盐中的转变。值得注意的是，除了Cr在熔盐中溶解形成多孔结构外，还发现由于金属 - 盐相互作用，逐渐形成了δ - A15 Cr相。Cr的这种相变与界面处Cr的配位环境变化有关。DFT和AIMD模拟通过揭示高温下它们的竞争相热力学以及探测熔盐在相关晶面的界面行为，为理解δ - A15 Cr相对于体心立方（bcc）Cr增强的稳定性提供了依据。这项研究为金属 - 熔盐界面的形态和化学演化提供了关键见解。多模态同步加速器分析与原子模拟的结合也为探索对能源应用至关重要的更广泛体系提供了机会。
