Radiation resistance in alloys by solute-defect trapping

非技术摘要：目前核反应堆中使用的材料无法满足未来反应堆先进设计的关键要求。特别是，它们对辐射损伤的抵抗力不足。我们在这里研究一种方法来增加材料的耐辐射性，其中少量添加精心选择的合金元素用于大大减缓这些材料的演化动力学。该方法利用了大量的准确数据，现在从高通量原子计算的社区筛选最有前途的合金元素。该研究建议采用最先进的纳米级实验来验证铜基体中的这种方法，其中锑已被预选为有前途的合金元素。这项工作还旨在确定这种材料设计方法是否可以与另一种方法相结合，依赖于纳米级沉淀物的自发形成，从而产生极端的抗辐射性。该研究将为两名研究生和几名本科生提供教育，重点是先进的材料合成和表征技术以及原子建模。将特别努力招收女生和代表性不足的少数民族学生。该研究将与教育相结合，以进一步发展和实施主动学习techniques.Technical Abstract：这一基础研究计划探讨了一种战略，设计单相材料的耐辐射损伤，通过使用小合金添加的溶质，陷阱点缺陷，以增加点缺陷的相互重组超过他们的消除在汇。虽然这种策略在过去已经被考虑过，并取得了令人鼓舞的结果，但它在很大程度上没有得到广泛的关注，因为没有可靠的方法来选择最好的溶质来捕获点缺陷。拟议的研究利用最近的建模进展来克服这些限制。具体而言，对于Cu基质，使用第一原理计算来计算溶质-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，Sb被确定为这些有前途的溶质之一。实验程序直接测量的相对重组率超过汇消除在照射过程中的稀释的Cu-Sb合金的加宽和漂移的薄标记层放置在战略位置的Cu薄膜的边界由Nb层，Cu/Nb界面提供接近完美的汇点缺陷消除。这些加宽和移位是在纳米尺度上使用原子探针层析成像（APT）和分析型扫描透射电子显微镜（TEM）测量的。此外，实施该方法以赋予在辐照下自组织的合金（例如Cu-Fe）抗辐照性，从而进一步延长其在辐照下的稳定性。通过结合这两种方法，点缺陷捕获和组成图案化，可以在辐射条件的极大扩展域中实现抗辐射性。实验程序的补充原子KMC模拟支持的数据分析，并探讨在溶质筛选阶段的简化的潜在影响。通过为本科生提供研究机会，并通过PI教授的课程中的计算模块将研究与教育相结合，扩大了该计划的影响。积极参与还提供开发，评估和传播主动学习技术。

NON-TECHNICAL ABSTRACT:Materials used in current nuclear reactors cannot meet key requirements of the advanced designs proposed for future reactors. In particular, their resistance to radiation damage is insufficient. We investigate here one approach to increase materials radiation resistance, where small additions of carefully selected alloying elements are used to drastically slow down the kinetics of evolution of these materials. The approach takes advantage of the large body of accurate data now available to the community from high-throughput atomistic calculations to screen the most promising alloying elements. The research proposes to employ state-of-the-art nanoscale experiments to validate this approach in a copper matrix, for which antimony has been pre-selected as a promising alloying element. The work also aims at determining whether this material design approach can be combined with another one, relying on the spontaneous formation of precipitates at the nanoscale, thus resulting in extreme radiation resistance. The research will provide education for two graduate students and several undergraduate students, with an emphasis on advanced materials synthesis and characterization techniques, and atomistic modeling. Special effort will be made to recruit female and underrepresented minority students. The research will be integrated with education to further develop and implement active learning techniques.TECHNICAL ABSTRACT:This fundamental research program examines a strategy for designing single phase materials resistant to radiation damage by using small alloying additions of solutes that trap point defects so as to increase point defect mutual recombination over their elimination at sinks. While this strategy has been considered in the past, and yielded encouraging results, it has not received widespread attention in large part because no reliable method was available to select the best solutes to trap point defect. The proposed research takes advantage of recent modeling advances to overcome these limitations. Specifically, for a Cu matrix, using first principles calculations to calculate solute-point defect interactions, and self-consistent mean-field theory to calculate defect and solute transport coefficients, Sb was identified as one of these promising solutes. The experimental program measures directly the relative rate of recombination over sink elimination during irradiation of dilute Cu-Sb alloys from the broadening and the drift of thin marker layers placed at strategic positions in a Cu thin film bounded by Nb layers, the Cu/Nb interfaces providing near perfect sinks for point defect elimination. These broadenings and shifts are measured at the nanoscale using atom probe tomography (APT) and analytical scanning transmission electron microscopy (TEM). In addition this approach is implemented for imparting radiation resistance to alloys that self-organizes under irradiation, such as Cu-Fe, so as to further extend their stability under irradiation. By combining the two approaches, point defect trapping and compositional patterning, radiation resistance can be achieved in a vastly extended domain of irradiation conditions. The experimental program is complemented by atomistic KMC simulations to support the data analysis and to explore the potential impact of simplifications made during the solute screening stage. The impact of the program is broadened by offering research opportunities to undergraduates and by integrating research with education through computational modules in courses taught by the PIs. Active engagement is also offered to develop, assess, and spread active learning techniques.