Self-Organization in Model Cu Alloys for High-temperature Irradiation Environments

技术概述：PI利用自组织反应获得在高温照射环境下本质稳定的材料。传统材料在这样的环境中通过脆化、偏析、蠕变和膨胀而降解，这是由于点缺陷不平衡地流向下沉造成的。为了克服这些不利的演化，这里使用自组织反应来引入高密度的稳定的点缺陷陷阱，从而促进复合。考虑了两种不同的自组织机制，包括弹道混合和热分解之间的竞争和级联内沉淀。通过同时激活这两种机制，复杂的核/壳纳米结构有望在相对应温度高达0.80的辐射下具有极大的稳定性和更好的机械性能。用CuWX型三元合金(X=Ag，Fe，Ni)对该方法进行了验证。用X射线衍射仪、透射电子显微镜、原子探针层析和原位电阻率等技术对离子辐照前后的薄膜进行了表征。原子模拟，包括动力学蒙特卡罗模拟，包括点缺陷的产生、复合和消除，被用来确定成分图案在高温和辐照下保持动态稳定的条件。该计划的影响通过为高级实验室课程开发一个新模块，强调纳米级沉淀和薄膜排序，通过为本科生提供研究经验，以及通过我们系的材料优势章节促进师生互动和拓展活动来扩大影响。非-技术摘要：为未来几代先进核电系统提出的设计依赖于需要在高温和长时间照射下运行的材料。目前的材料不能在如此恶劣的环境中安全、可靠和经济地运行。目前的研究计划建议利用自组织反应来设计将产生复杂纳米级沉淀物的材料。通过合理地选择合金元素，这些纳米析出物将被优化，以稳定这些材料的组织和力学性能。由此产生的高强度、高温材料也将对其他能源生产系统产生兴趣。这项研究将为两名研究生和两名本科生提供教育，重点是先进的材料合成和表征技术以及原子建模。将特别努力招收女性和代表性不足的少数民族学生。旨在鼓励高中生从事STEM职业的外展活动将与我们的系物质优势学生分会一起启动和协调。

TECHNICAL SUMMARY:The PIs utilize self-organization reactions to obtain materials that are intrinsically stable under high-temperature irradiation environments. Conventional materials degrade through embrittlement, segregation, creep, and swelling in such environments, caused by the unbalanced flow of point defects to sinks. In order to overcome these detrimental evolutions, self-organization reactions are used here to introduce a high density of stable point-defect traps, thus enhancing recombination. Two separate self-organization mechanisms are considered, involving the competition between ballistic mixing and thermal decomposition, and intra-cascade precipitation. By activating both mechanisms simultaneously, complex core/shell nanostructures are expected with vastly improved stability under irradiation at homologous temperatures as high as 0.80 and with improved mechanical properties. Model Cu-W-X ternary alloys (X = Ag, Fe, Ni) are used to test and validate the approach. Thin films of these alloys are characterized before and after ion irradiation with a combination of techniques, including XRD, TEM, atom probe tomography, and in situ electrical resistivity. Atomistic simulations, including kinetic Monte Carlo simulations that include the creation, recombination and elimination of point defects, are employed to identify the conditions for compositional patterns to remain dynamically stable at elevated temperature and under irradiation. The impact of the program is broadened by developing a new module for a senior laboratory course, highlighting nanoscale precipitation and ordering in thin films, by providing research experience for undergraduates, and by promoting faculty-student interactions and outreach activities through our departmental Material Advantage Chapter.NON-TECHNICAL SUMMARY:The proposed design for the future generations of advanced nuclear power systems rely on materials that need to operate at elevated temperatures and under prolonged irradiation. Current materials cannot operate safely, reliably, and economically in such harsh environments. The present research program proposes to utilize self-organization reactions to design materials that will produce complex nano-scale precipitates. By judicious choice of alloying elements, these nano-precipitates will be optimized to stabilize the microstructure and the mechanical properties of these materials. The resulting high-strength, high-temperature materials will also be of interest for other energy production systems. The research will provide education for two graduate and two 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. Outreach activities aimed at encouraging high-school students to pursue STEM careers will be initiated and coordinated with our departmental Material Advantage student chapter.