Collaborative Research: Compositional and Atomic-Scale Ordering Effects on Aqueous Passivation of Binary BCC and FCC Alloys

与不锈钢不同，许多其他金属在潮湿环境中会受到严重腐蚀。腐蚀是一种破坏性的电化学反应，在航空航天工业和基础设施维修（如建筑物、桥梁、饮用水管道、核/常规发电和核废料储存）中会造成重大的人员和经济损失。腐蚀甚至会限制生物医学植入物的使用寿命。当耐腐蚀的金属合金暴露于水中的腐蚀剂时，它们自然会形成一层只有几纳米厚的薄薄的保护表面膜，称为氧化物。相应的腐蚀速率，由于金属的损失，是小于1微米每年，导致超长的使用寿命。这个合作研究项目的目标是利用模拟和实验来发展对合金上氧化物形成过程的原子尺度的理解。这些知识将用于指导模型，告知下一代耐腐蚀金属合金的设计。该项目还包括一系列活动，以扩大代表性不足的少数民族对科学的参与，同时提供材料电化学和腐蚀科学培训的机会。该合作项目的目标是开发二元合金的解析和数值水钝化模型，并使用多模态实验、基于第一性原理的量子力学模型和动力学蒙特卡罗模拟来验证它们。解缠的关键参数包括合金的晶体结构、成分、化学短程序和电解质组成。在这项研究中提出的科学问题是，短程顺序是否可以用作材料加工旋钮，可以调整以提高耐腐蚀性。该项目整合了多种专业技术，包括：(i)线性扫描伏安法和计时库容法的电化学技术。（ii）电感耦合等离子体质谱法监测合金成分氧化溶解，与理论预测进行相关分析。（iii）利用同步加速器光源表征短程有序参数。（iv）超高真空扫描探针显微镜对合金单晶表面近程有序进行实空间统计表征。密度泛函理论推导出的原子间电位作为合金钝化动力学蒙特卡罗模拟和大尺度蒙特卡罗重整化群技术的输入，以确定短程有序对现场渗透阈值的影响。该项目还通过三项努力解决劳动力供应需求，以确保国家基础设施的安全和现代化。第一种是让学生在跨学科的研究环境中接受合金热力学、计算建模、电化学和腐蚀方面的训练。第二部分为本科生和研究生开发新的电化学材料课程，以提高工作能力。第三个是STEAM （STEM加艺术）“材料炼金术”周末项目，能够吸引K-9中代表性不足的学生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARY Unlike stainless steels, many other metals undergo severe corrosion in wet environments. Corrosion is a destructive electrochemical reaction that can impose significant human and financial loss in the aerospace industry and in infrastructure repair (e.g., buildings, bridges, potable water pipelines, nuclear/conventional power generation and nuclear waste storage). Corrosion can even limit the lifetime of biomedical implants. When corrosion resistant metallic alloys are exposed to corrosive agents occurring in water, they naturally evolve a thin protective surface film only a few nanometers thick called an oxide. The corresponding corrosion rate, as a result of metal loss, is less than one micrometer per year resulting in exceptionally long service lifetimes. The goal of this collaborative research project is to use simulations and experiments to develop an atomic scale understanding of the oxide formation process that occurs on alloys. This knowledge will be used to guide models that inform the design of next generation corrosion-resistant metallic alloys. This project also includes a range of activities to broaden participation of underrepresented minorities in science while providing an opportunity for training in materials electrochemistry and corrosion science. TECHNICAL SUMMARY The goal of this collaborative project is to develop analytical and numerical aqueous passivation models of binary alloys and validate them using multimodal experiments, first-principles-based quantum mechanical models, and kinetic Monte Carlo simulations. Key parameters to disentangle include contributions from alloy crystal structure, composition, chemical short-range order, and composition of electrolyte. The scientific question posed in this research is whether short-range order can be used as a materials processing knob that can be tuned to enhance corrosion resistance. The project integrates a variety of specialized techniques including: (i) Electrochemical techniques of linear sweep voltammetry and chronocoulometry. (ii) Inductively coupled plasma mass spectroscopy to monitor oxidative dissolution of alloy components for correlative analysis with theoretical predictions. (iii) Characterization of short-range order parameters using synchrotron light sources. (iv) Ultra-high vacuum scanning probe microscopy for real-space statistical characterization of short-range order on alloy single crystal surfaces. (v) Density functional theory-derived interatomic potentials as inputs for both kinetic Monte Carlo simulations of alloy passivation and large-scale Monte Carlo renormalization group techniques for determining the effect of short-range order on site percolation thresholds. The project also addresses workforce supply needs for securing and modernizing national infrastructure through three efforts. The first involves students in interdisciplinary research environments with training in thermodynamics of alloys, computational modeling, electrochemistry, and corrosion. The second develops new electrochemical materials courses for undergraduate and graduate students to improve workforce competencies. The third is a STEAM (STEM plus Arts) “Material Alchemy” weekend program capable of engaging underrepresented students in K-9.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.