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

技术总结：PI利用自组织反应获得在高温辐照环境下本质稳定的材料。传统材料在这样的环境中由于点缺陷向下沉的不平衡流动而通过脆化、偏析、蠕变和膨胀而劣化。为了克服这些不利的演变，自组织反应在这里被用来引入一个高密度的稳定点缺陷陷阱，从而提高重组。两个独立的自组织机制被认为是，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，预期复杂的核/壳纳米结构在高达0.80的同系温度下的辐照下具有大大改善的稳定性，并且具有改善的机械性能。以Cu-W-X三元合金（X = Ag，Fe，Ni）为例进行了验证。这些合金的薄膜的特征在于之前和之后的离子辐照与技术的组合，包括XRD，TEM，原子探针断层扫描，和原位电阻率。原子模拟，包括动力学Monte Carlo模拟，包括创建，重组和消除点缺陷，用于确定组成模式在高温下和辐照下保持动态稳定的条件。该计划的影响是扩大了开发一个高级实验室课程的新模块，突出纳米沉淀和有序薄膜，通过为本科生提供研究经验，并通过促进师生互动和推广活动，通过我们的部门材料优势章。非技术摘要：先进的核电系统的未来几代的拟议设计依赖于需要在高温和长时间照射下运行的材料。目前的材料无法在如此恶劣的环境中安全、可靠和经济地运行。目前的研究计划提出利用自组织反应来设计将产生复杂的纳米级沉淀物的材料。通过明智地选择合金元素，这些纳米析出物将被优化以稳定这些材料的微观结构和机械性能。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影响。该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。将特别努力招收女生和代表性不足的少数民族学生。旨在鼓励高中生追求干事业的推广活动将启动，并与我们的部门材料优势学生章协调。

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.