CAREER: Understanding the Synergistic Effects of Irradiation and Molten Salt Corrosion on NiCr Alloys

核能约占美国电力组合的20%。随着气候变化促使许多国家追求清洁能源，而太阳能、风能和其他可再生资源可能不够可靠，无法满足能源需求，核能有望填补可持续清洁能源转型的空白。基于熔盐的先进反应堆由于其在安全性和高效性方面的显著优势，正受到人们的积极研究。然而，由于极端条件，包括高温（高于700摄氏度），辐射暴露（中子和裂变碎片）以及腐蚀性环境（熔盐），熔盐中的结构材料容易失效。该奖项由美国国家科学基金会材料研究部凝聚态物质和材料理论项目资助，PI旨在解决辐射和高温腐蚀对镍基合金的协同效应这一特殊挑战，在这一领域，实验数据有时会显示出关于辐射在合金腐蚀中的作用的相互矛盾的结论。该项目的目标将基于计算的角度来实现，其中将使用和开发多尺度计算方法，并将通过实验表征来补充结果。该项目还强调为学生和公众提供教育和培训机会。本科生和研究生将获得尖端计算技术的实践研究经验，扩展他们在材料科学研究方面的知识和技能。外展活动将针对宾夕法尼亚州中央县学区的当地大学预科学生，特别是那些来自代表性不足的少数民族社区的学生。此外，还将制作一系列介绍核能各个方面的教育录像，并通过网络渠道向公众传播。这些活动有助于培养清洁能源部门未来的劳动力，并提高对核能重要性和相关挑战的认识。技术总结：由于熔盐有望成为应对气候变化的脱碳能源解决方案的一部分，人们对依赖熔盐应用的先进核反应堆的兴趣持续增长。高温熔盐（氟化物盐为主要候选）对结构材料（镍基合金为主要候选）的腐蚀和辐照是影响长期可靠性的寿命限制问题。然而，目前严重缺乏基于基本原理的结构材料熔盐腐蚀预测能力。一个特别的挑战是辐射和高温腐蚀的协同效应，其中实验数据有时显示关于辐射在调解合金腐蚀中的作用的相互矛盾的结论。该项目旨在从计算角度解决这个难题，并辅以实验表征。提出了一种基于密度泛函理论的第一性原理计算、基于反应分子动力学的界面动力学和基于动力学蒙特卡罗的微观结构演化的多尺度策略。这种多尺度策略不仅可以解决辐射和腐蚀耦合的假设，而且还提供了基于基本理解的微观结构变化的进化图像的工具。这些努力将有助于先进反应堆的发展和更广泛的领域，如功能材料合成、热储存和化学精炼。两个主要的研究目标包括：1)推进对活性熔盐腐蚀机制的基本认识；2)了解辐射和合金-盐界面腐蚀的协同效应。与这些研究目标相结合，主要的教育目标包括培养下一代清洁能源部门的专业人员，同时提高对核能重要性及其相关挑战的认识。本科生和研究生都将获得使用最先进的计算技术的实际研究技能，从而拓宽他们在材料科学研究方面的专业知识。外展工作将针对当地学区的大学预科学生，特别关注那些来自代表性不足的少数族裔社区的学生。此外，还将制作一系列突出核能不同方面的教育录象集，并在网上分享，供公众传播。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。

NONTECHNICAL SUMMARYNuclear energy contributes around 20% of the U.S. electricity portfolio. As climate change pushes many countries to pursue clean energy, and solar, wind, and other renewable resources might not be reliable enough to keep up with the energy demand, nuclear power is promising to fill the gap for a sustainable clean energy transition. Advanced reactors that rely on the application of molten salts are being under active investigation due to their major advantages in safety and efficiency. However, structural materials in molten salts are susceptible to failure due to extreme conditions, including high temperatures (higher than 700 degrees Celsius), radiation exposure (neutron and fission fragments), and corrosive environments (molten salts). Through this award, funded by the Condensed Matter and Materials Theory Program in the Division of Materials Research at NSF, the PI aims to address a particular challenge regarding the synergistic effect of radiation and high-temperature corrosion on Ni-based alloys, where experimental data sometimes shows conflicting conclusions regarding the role of radiation in mediating the corrosion of alloys. This project goal will be achieved based on a computational perspective, where multi-scale computational methods will be used and developed, and the results will be complemented by experimental characterization. This project also emphasizes educational and training opportunities for students and the public. Undergraduate and graduate students will gain hands-on research experiences with cutting-edge computational techniques, expanding their knowledge and skills in materials science research. Outreach activities will be targeted toward local pre-college students in Centre County School District, Pennsylvania, especially those from underrepresented minority communities. Additionally, a series of educational video episodes that feature various aspects of nuclear energy will be produced and disseminated via online channels to the public. These activities contribute to fostering the future workforce for the clean energy sector and enhancing awareness of the importance of nuclear energy and associated challenges. TECHNICAL SUMMARYThe interest in advanced nuclear reactors that rely on molten salt applications continues to grow due to their promise to be part of an energy solution for decarbonization to combat climate change. High-temperature molten salt (fluoride salt as a major candidate) corrosion and irradiation of structural materials (Ni-based alloys as a major candidate) is a life-limiting problem for long-term reliability. However, a fundamentals-based predictive capability for evaluating molten salt corrosion of structural materials under irradiation is seriously lacking. A particular challenge is the synergistic effect of radiation and high-temperature corrosion, where experimental data sometimes shows conflicting conclusions regarding the role of radiation in mediating the corrosion of alloy. This project aims to address this conundrum from a computational perspective, complemented by experimental characterization. A multi-scale strategy which encompasses first-principles calculations based on density function theory, interface dynamics based on reactive molecular dynamics, and microstructural evolution based on kinetic Monte Carlo, is proposed. Not only can this multi-scale strategy address the hypotheses on how radiation and corrosion are coupled, it also provides the tools to obtain an evolutional picture of microstructural changes that is based on fundamental understanding. These efforts will contribute to advanced reactor development and broader fields such as functional materials synthesis, thermal storage, and chemical refinement. The two major research objectives include i) advancing the fundamental understanding of active molten salt corrosion mechanisms and ii) understanding the synergetic effects of radiation and corrosion at the alloy-salt interface. Integrated with these research objectives, the major educational objectives include cultivating the next generation of professionals for the clean energy sector while also raising awareness about the significance of nuclear energy and its associated challenges. Both undergraduate and graduate students will acquire practical research skills using state-of-the-art computational techniques, thereby broadening their expertise in materials science research. Outreach efforts will be directed toward pre-college students in the local school district, with a particular focus on those from underrepresented minority communities. Furthermore, a collection of educational video episodes highlighting different facets of nuclear energy will be produced and shared online for public dissemination.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.