RII Track-4: Experimentally-informed Mesoscale Modeling of Anisotropic Grain Boundary Solute Segregation in Nanocrystalline Alloys

RII Track-4：纳米晶合金中各向异性晶界溶质偏析的基于实验的介观尺度建模

• 批准号: 2033327
• 负责人: Fadi Abdeljawad
• 金额: $ 18.36万
• 依托单位: Clemson University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-02-01 至 2023-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2033327&HistoricalAwards=false
• 关键词: RII; Track; Experimentally; informed; Mesoscale

Nearly all structural materials are polycrystalline systems; their microstructures are comprised of crystalline grains that are joined at internal interfaces, termed grain boundaries (GBs). Owing to their nanometric grain size, nanocrystalline (NC) metals exhibit unique combinations of properties that are not commonly observed in their coarse-grained counterparts. However, NC metals are susceptible to rapid grain coarsening during processing or under service conditions, which in turn limits their use in many engineering applications, such as structural, energy, and electronics. Recent experimental findings suggest GB solute segregation as a design strategy to manipulate interface properties and develop thermally stable NC metals. Through coordinated experimental and computational studies, the main research objective of this project is to gain fundamental insights into the role of GB geometry in solute segregation and the resultant impact on the thermal stability of NC alloys. The experimental portion of this project will be conducted at the Center for Integrated Nanotechnologies at Sandia National Laboratories (CINT-SNL). This project will uniquely position the PI to be at the forefront of innovative research on nanomaterials, metallurgy and interface physics, and it will serve as a catalyst for future collaborations and partnerships between Clemson University and CINT-SNL. Further, this project provides a fertile avenue to train future generation of engineers and scientists with the interdisciplinary skill set necessary for careers in knowledge-intensive industries in South Carolina, which is an emerging advanced manufacturing hub.While great strides have been recently made towards the use of GB solute segregation to design thermally stable NC metals, our current understanding is still lacking as most existing efforts rely on the isotropy assumption in segregation - solute atoms segregate equally and uniformly to all GBs. This is an overly simplistic assumption as GB properties are greatly influenced by the boundary’s geometry. This project advances the current understanding of interface segregation by elucidating the impact of GB geometry on solute segregation behavior. The experimental thrust of this project will be performed at the Center for Integrated Nanotechnologies at Sandia National Laboratories (CINT-SNL), which will allow the PI to take advantage of a suite of cutting-edge high-resolution microscopy facilities. The PI will use tools, including aberration-corrected scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction at CINT-SNL to conduct in situ high-temperature experiments, detailed tomographic reconstructions of samples, chemical mapping, and orientation imaging microscopy of texture and GB character in NC systems with the goal of characterizing and quantifying GB solute concentration for a wide range of GB types. The PI will perform analysis, employing analytical models of interface adsorption, of the experimental data to obtain segregation energies that serve as input parameters to a recently developed mesoscale model of GB segregation and microstructural evolution in NC alloys. Using the experimentally informed model, we will perform systematic computational studies to elucidate the impact of anisotropic GB solute segregation on grain growth and thermal stability of NC alloys.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.

几乎所有的结构材料都是多晶系统；它们的微观结构由在内部界面连接的晶体颗粒组成，称为晶界(GBs)。由于其纳米级的晶粒度，纳米晶(NC)金属表现出在粗晶金属中不常见的独特的性能组合。然而，NC金属在加工过程中或在使用条件下容易迅速粗化，这反过来又限制了它们在许多工程应用中的使用，如结构、能源和电子产品。最近的实验结果表明，GB溶质偏析是一种控制界面性质和开发热稳定性NC金属的设计策略。通过实验和计算相结合的研究，本项目的主要研究目标是深入了解GB几何结构在溶质偏析中的作用及其对NC合金热稳定性的影响。该项目的实验部分将在桑迪亚国家实验室集成纳米技术中心(CINT-SNL)进行。该项目将使PI独一无二地站在纳米材料、冶金和界面物理创新研究的前沿，并将成为克莱姆森大学和CINT-SNL未来合作和伙伴关系的催化剂。此外，该项目为培养未来一代工程师和科学家提供了一条肥沃的途径，为南卡罗来纳州知识密集型行业的职业生涯提供了必要的跨学科技能集。南卡罗来纳州是一个新兴的先进制造业中心。尽管最近在使用GB溶质分离设计热稳定的NC金属方面取得了很大进展，但我们目前的理解仍然不足，因为大多数现有的努力依赖于分离中的各向同性假设-溶质原子平等而均匀地偏析到所有GB。这是一个过于简单的假设，因为GB属性很大程度上受边界几何形状的影响。本项目通过阐明GB几何形状对溶质偏析行为的影响，促进了当前对界面偏析的理解。该项目的实验推力将在桑迪亚国家实验室集成纳米技术中心(CINT-SNL)进行，这将使PI能够利用一套尖端的高分辨率显微镜设施。PI将使用包括像差校正扫描电子显微镜、能量色散X射线光谱和CINT-SNL X射线衍射在内的工具，在NC系统中进行现场高温实验、详细的样品层析重建、化学测绘和纹理和GB字符的定向成像显微镜，目标是表征和量化各种GB类型的GB溶质浓度。PI将利用界面吸附的分析模型对实验数据进行分析，以获得偏析能，作为最近开发的关于NC合金中GB偏析和组织演变的中尺度模型的输入参数。使用经验模型，我们将进行系统的计算研究，以阐明各向异性GB溶质偏析对NC合金的晶粒生长和热稳定性的影响。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

The grain boundary stiffness and its impact on equilibrium shapes and boundary migration: Analysis of the Σ 5, 7, 9, and 11 boundaries in Ni

晶界刚度及其对平衡形状和晶界迁移的影响：Ni 中 Σ 5、7、9 和 11 晶界的分析

• DOI: 10.1016/j.actamat.2021.117220
• 发表时间: 2021
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: Moore, Robert D.;Beecroft, Timothy;Rohrer, Gregory S.;Barr, Christopher M.;Homer, Eric R.;Hattar, Khalid;Boyce, Brad L.;Abdeljawad, Fadi
• 通讯作者: Abdeljawad, Fadi

Plateau–Rayleigh instability with a grain boundary twist

• DOI: 10.1063/5.0103658
• 发表时间: 2022-10
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: O. Hussein;D. Keith Coffman;K. Hattar;E. Lang;S. Dillon;F. Abdeljawad

Interface nucleation rate limited densification during sintering

• DOI: 10.1016/j.actamat.2022.118448
• 发表时间: 2022-10
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: S. Dillon;Yonghui Ma;J. Oyang;D. Coffman;Omar Hussein;K. Hattar;F. Abdeljawad