CAREER:Quantifying Radiation Damage in Metals with Wigner Energy Spectral Fingerprints

对金属“损伤”的概念仍然难以量化。金属是我们最重要的结构材料之一，是建筑、桥梁、核反应堆等一切事物的支柱。如果我们有一种通用的方法来测量损坏，我们就能更好地预测金属什么时候会失效，测量它们在使用过程中的退化程度，并设计出更耐用、更经济的新金属。存储能量指纹的使用被提议作为一种量化任何损伤过程对金属损伤的方法。我们把辐射损伤作为一种理想的方法来制造金属中发现的所有类型的缺陷。一个双管齐下的实验和模拟方法将用于量化和理解这些存储的能量指纹，将它们直接与损伤产生的缺陷联系起来。这项工作的直接应用范围从调和离子和中子辐照之间的差异，到预测由于辐射损伤而导致的材料性质变化，再到验证铀浓缩离心机的历史使用。这种加深的理解也将是降低学习障碍的关键，为实践教学和将更多代表性不足的少数民族（URM）学生纳入目前STEM中多元化程度最低的领域之一创造全新的机会。由于缺乏对损伤过程中产生的微结构缺陷的精确数量的了解，我们了解材料对损伤的反应的能力受到了限制。这一问题在辐射材料科学领域最为普遍，由于缺乏可测量的辐射损伤单位，在电离辐照下导致材料性能退化的定量机制继续模糊不清。如果已知损坏材料中每个缺陷的完整种群，则可以利用现有的结构-性能关系预测其材料性能。我们建议使用存储能量指纹来可视化由任何类型的损伤，特别是辐射造成的全部缺陷。我们从一个长期被忽视的观点中获得灵感，即辐射损伤应该像非晶化或冷作用一样储存能量。这一想法被扩展到描述金属中所有形式的微结构损伤，以一种可测量的方式揭示缺陷的责任。利用时间加速的平行复制动力学模拟和超快速纳米量热测量，我们将在中尺度上直接将模拟和测量的存储能量释放联系起来，并具有原子性的理解。这将使受损金属的存储能量指纹的后验测量，揭示原子结构和缺陷的数量负责。因此，我们试图提供由损伤引起的缺陷的全貌，展示一种测量它们的方法，使用原子模拟解释它们的演变，并创建统一的理论来预测由金属损伤引起的缺陷结构和由此产生的材料特性。

Non-Technical The concept of "damage" to a metal remains difficult to quantify. Metals are among our most important structural materials, providing the backbone to everything from buildings, to bridges, to nuclear reactors. If we had a universal way to measure damage, we would be able to better predict when metals would fail, measure their degradation during service, and design new metals to be both longer-lasting and more economical. The use of stored energy fingerprints is proposed as a way to quantify damage to metals from any damaging process. We focus on radiation damage as an ideal way to make all the types of defects found in metals. A two-pronged experimental and simulation approach will be used to quantify and understand these stored energy fingerprints, relating them directly to the defects created by damage. Immediate applications of this work range from reconciling the differences between ion and neutron irradiation, to predicting material property changes due to radiation damage, to verifying the historical usage of uranium enrichment centrifuges. This enhanced understanding will also be the key to lowering the barriers to its study, creating completely new opportunities for both hands-on instruction and inclusion of more underrepresented minority (URM) students into what is currently one of the least diverse fields in STEM.Technical Our ability to understand how materials respond to damage is limited by our lack of understanding about the precise populations of microstructural defects created during damage processes. Nowhere is this issue more prevalent than in the field of radiation materials science, where the lack of a measurable unit of radiation damage continues to obfuscate the quantitative mechanisms responsible for the degradation of material properties under ionizing irradiation. Were the full populations of every defect in a damaged material to be known, then its material properties could be predicted with existing structure-property relations. We propose to use stored energy fingerprints to visualize the full plethora of defects resulting from damage of any kind, particularly irradiation. We draw inspiration from a long-neglected idea stating that radiation damage should store energy like amorphization or cold work. This idea is extended to describe all forms of microstructural damage in metals, in a measurable way which reveals the defects responsible. Using time-accelerated parallel replica dynamics simulations and ultra-fast nanocalorimetric measurements, we will directly link simulated and measured stored energy releases at the mesoscale, with atomistic understanding. This will enable a posteriori measurements of stored energy fingerprints of damaged metals, revealing the atomic configurations and quantities of defects responsible. Thus we seek to provide the full picture of defects resulting from damage, demonstrate a method to measure them, explain their evolution using atomistic simulations, and create unifying theories to predict the defect structures and resultant material properties resulting from damage in metals.