A novel approach for increasing radiation resistance of multicomponent alloys using synergistic solutes

目前核反应堆中使用的非技术材料由于持续暴露在高能粒子的照射下而发生有害的演化，导致使用寿命有限。这项研究探索了一种新的方法，通过少量添加合金元素来显著抑制其中一些演化的动力学。因为现在已经知道，添加一种溶质只能不完美地满足这一目标所需的许多功能，所以这里追求的是协同元素的组合。原子模拟和建模被用来确定这些合金化元素的最有效组合，并设计了纳米尺度的实验来测试和验证所提出的方法在包括铜基合金在内的模型金属合金上的有效性。这项研究广泛地影响了对先进能源技术至关重要的新材料的合金设计战略的发展。该计划通过支持两名研究生和几名本科生，支持科学、技术、工程和数学领域的劳动力发展。通过开发建模模块和在PIS教授的课程中实施主动学习技术，该研究与本科教育相结合。技术总结这项基础研究调查了用于捕获点缺陷的溶质添加在抗辐射合金设计中的使用。其动机源于这样一种认识，即点缺陷向晶界和位错等下沉的持续流动是导致材料在辐照过程中长期降解的主要因素。此外，在合金中，缺陷焊剂经常与化学焊剂耦合，导致辐照引起的偏析，甚至在沉淀处析出。一个有吸引力的解决方案是通过加入点缺陷捕获溶质来增加点缺陷复合。挑战是确定能够有效捕捉点缺陷的最佳溶质，而不会由于缺陷通量而被溶质阻力逐渐从基质中去除。这项研究引入了使用协同溶质来满足这些多重要求的新想法，使用第一性原理计算来确定溶质点缺陷相互作用，并使用自洽平均场理论来计算缺陷和溶质输运系数。该实验方案旨在直接测量溶质对整个空位扩散和溶质阻力的影响。这是通过使用原子探针层析术测量放置在铜薄膜中关键位置的薄标记层的展宽和漂移来实现的。提出的实验程序得到了动力学蒙特卡罗模拟的补充。这项研究的更广泛影响包括开发对先进能源技术至关重要的新材料的合金设计战略。该项目还将与法国CEA的T.Schuler博士在点缺陷和溶质耦合传输的建模方面建立国际合作。此外，研究和教学将通过开发本科课程的计算模块和通过研究经验指导本科生来整合。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYMaterials employed in current nuclear reactors suffer from detrimental evolutions triggered by their continuous exposure to irradiation by energetic particles, resulting in limited service life. The research explores a novel approach to dramatically suppress the kinetics of some of these evolutions through minor addition of alloying elements. Since it is now known that addition of one solute can only imperfectly meet the many functions required for that goal, here a combination of synergistic elements is pursued. Atomistic simulations and modeling are used to identify the most effective combination of such alloying elements, and nanoscale experiments are designed to test and validate the proposed approach on model metallic alloys, including Cu-based alloys. This research impacts broadly the development of alloy design strategies for new materials that are critical to advanced energy technologies. The program supports the development of workforce in the Science, Technology, Engineering and Math fields by supporting two graduate students and several undergraduate students. The research is integrated with undergraduate education by developing modeling modules and by implementing active learning techniques in the courses taught by the PIs.TECHNICAL SUMMARYThis fundamental research investigates the use of solute additions for trapping point defects toward the design of radiation resistant alloys. The motivation stems from the recognition that the sustained fluxes of point defects to sinks such as grain boundaries and dislocations is the main factor contributing to the long-term degradation of materials during irradiation. In alloys, moreover, defect fluxes often couple to chemical fluxes, resulting in irradiation-induced segregation or even precipitation at sinks. An attractive solution is to increase point-defect recombination by adding point defect-trapping solutes. The challenge is to identify the best solutes that can trap point defect efficiently, without being progressively removed from the matrix by solute drag due to defect fluxes. The proposed research introduces the novel idea of using synergistic solutes to meet these multiple requirements, employing first principles calculations to determine solute-point defect interactions and self-consistent mean-field theory to calculate defect and solute transport coefficients. The experimental program aims at measuring directly the effect of solute on the overall vacancy diffusion and on solute drag. This is achieved by measuring the broadening and the drift of thin marker layers placed at strategic positions in a Cu thin film using atom probe tomography. The proposed experimental program is complemented by kinetic Monte Carlo simulations. The broader impact of the research includes the development of alloy design strategies for new materials that are critical to advanced energy technologies. The project will also establish an international collaboration with Dr. T. Schuler, from CEA, France, on the modeling of point defects and solute coupled transport. In addition, research and teaching will be integrated by developing computational modules for undergraduate courses and by mentoring undergraduate students through research experiences.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.