Collaborative Research: Bridging the atomic scale and the mesoscale in the characterization of defect production and evolution in high entropy alloys

合作研究：在高熵合金缺陷产生和演化表征中连接原子尺度和介观尺度

• 批准号: 2005006
• 负责人: Djamel Kaoumi
• 金额: $ 28.19万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2005006&HistoricalAwards=false
• 关键词: Collaborative; Research; Bridging; atomic; scale

NON-TECHNICAL SUMMARYDeveloping high strength materials that can withstand significant amounts of radiation and deformation are critical to advance many technical applications, including efficient nuclear energy production and space exploration. High entropy alloys (HEAs) are emerging as promising high strength and radiation-resistant materials as HEAs contain a mix of many elements that disrupt the chemical ordering. The focus of this research is to gain fundamental understanding at the atomic level on how the complexity of chemical disorder interferes with the formation and evolution of undesirable defects that weakens the material. To gain these insights, state of the art analytical and imaging techniques will be used to reveal how an atomic sized defect in the material evolves and how the chemical disorder interferes and halts this undesirable process. Such insights are needed to develop the optimal alloys with high radiation resistance, high strength and high stability that would not only enable new advanced power generating technologies with high efficiency and low or zero carbon emission but more generally, could transform many technical fields related to energy and space. Students working on the project will develop in-depth understanding on chemistry and physics of materials and defects in solids and gain experience in important techniques in material science. International student exchange and national internship opportunities are offered to the graduate students involved in the project. A wide range of research opportunities and outreach activities are provided to undergraduates and high school students throughout the period of the project where participation of underrepresented groups are actively encouraged. TECHNICAL SUMMARYHigh entropy alloys (HEAs) are emerging as an outstanding class of materials due to their excellent mechanical properties and high radiation tolerance as a result of their unique electronic structure. Chemical disorder and compositional fluctuations in these alloys have large effects on energy dissipation and response to irradiation. While previous transmission electron microscopy (TEM) and other studies showed that damage accumulation was suppressed by increasing chemical disorder, they could not reveal vacancy clusters below 2 nm leaving critical gap in understanding defect formation and buildup in these alloys. The proposed research aims to experimentally monitor defect formation on atomistic scale and their buildup to large clusters and voids by combining in-situ and ex-situ positron annihilation spectroscopy (PAS) with in-situ and ex-situ TEM to capture isolated vacancies, small vacancy clusters, larger clusters and voids, thus bridge the gap between the atomic scale and mesoscale characterization of radiation induced defects in HEAs. The use of In-situ PAS and In-situ TEM measurements both coupled with ion irradiation offers a picture of the defect dynamics including production, annihilation and evolution, on atomic scale (for PAS) and mesoscale (for TEM). The proposed research is expected to reveal the effects of chemical disorder on defect formation, migration and evolution in a radiation environment and reveal the damage and annealing mechanisms in Single -Phase Concentrated Solid Solution alloys (SP-CSAs) and HEAs through the study of defect production from collision cascades on an atomic and mesoscale level in alloys with increasing chemical complexity from one to five constituents.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.

非技术摘要可以承受大量辐射和变形的高强度材料对于推进许多技术应用至关重要，包括有效的核能生产和太空探索。高熵合金（HEAS）作为有希望的高强度和抗辐射材料而出现，因为HEAS包含了破坏化学秩序的许多元素的混合物。这项研究的重点是在原子水平上获得基本的理解，即化学障碍的复杂性如何干扰削弱材料的不良缺陷的形成和演变。 为了获得这些见解，将使用最先进的分析和成像技术来揭示材料中的原子大小缺陷如何发展以及化学障碍如何干扰和停止这种不良过程。 需要这样的见解来开发具有高辐射抗性，高强度和高稳定性的最佳合金，这不仅可以使新的高级发电技术具有高效率，低或零碳排放，而且更普遍地可能会改变许多与能源和空间相关的技术领域。从事该项目的学生将对材料的化学和物理学以及固体缺陷的化学和物理学有深入的了解，并获得材料科学重要技术的经验。为参与该项目的研究生提供了国际学生交流和国家实习机会。在整个项目的整个期间，都为本科生和高中生提供了广泛的研究机会和外展活动，积极鼓励代表性不足的团体的参与。技术摘要熵合金（HEAS）由于其独特的电子结构而导致其出色的机械性能和高辐射耐受性，因此成为出色的材料类别。这些合金中的化学障碍和组成波动对能量耗散和对辐射的反应具有很大的影响。虽然先前的透射电子显微镜（TEM）和其他研究表明，化学障碍抑制了损伤积累，但它们无法揭示低于2 nm以下的空位簇，而在理解这些合金中缺陷的形成和堆积方面，危险差距。 拟议的研究旨在通过将原位和原位的正面正电子净化光谱（PAS）与原子式和原位tem捕获孤立的空缺，从而在较小的空置夹，较大的浮标之间，在较大的空缺之间，在较大的空置范围内，在较大的空置中，在较大的空置范围内，通过隔离式的范围，在较小的空置中，弥合了gap的范围，从而在原子量表上进行实验监测原子量表及其堆积的缺陷形成及其堆积为大型聚类和空隙。 HEAS中的缺陷。在原子量表（用于PAS）和中尺度（用于TEM）上，使用原位PAS和原位测量均与离子辐照相结合的图片，包括产量，an灭和进化，包括生产，an灭和进化。预计拟议的研究预计将揭示化学障碍对辐射环境中缺陷形成，迁移和进化的影响，并揭示单个相浓缩的固体溶液合金（SP -CSA）中的损伤和退火机制，通过研究造成造成的化合物和Messoscale级别的化合物量的造成五质量的化合物的造成的缺陷产生的缺陷产生，并揭示出损害和退火机制。使用基金会的知识分子优点和更广泛的审查标准，通过评估被认为值得支持。