Fundamental Insights into Multi-element Grain Boundary Segregation in Nanocrystalline Alloys

该奖项支持研究和教育活动，旨在获得对多种元素物种到晶界的分离的基本见解，以及它如何影响纳米晶金属合金的晶粒生长。几乎所有的功能材料和结构材料都是多晶体系；它们是由不同取向的晶粒组成的，这些晶粒在内部界面上连接在一起，称为晶界。金属的晶粒尺寸和分布极大地影响许多工程性能，包括机械、热学和电学。例如，金属的机械强度随着晶粒尺寸的减小而迅速增加。然而，由于其晶粒尺寸小，晶界密度高，纳米晶材料通常在结构上不稳定。因此，它们经历了快速的晶粒生长，这限制了它们在许多技术应用中的使用。在这个项目中，PI将研究多种元素在多组分合金中晶界的偏析及其在晶粒生长中的作用。该研究涉及理论发展和数学模型的数值实现，将用于模拟晶界偏析动力学和晶粒生长动力学。这个项目的主要重点是由三种不同类型的元素组成的金属合金。该项目位于材料科学和应用数学的交叉点，将影响材料物理学、化学热力学和纳米技术的许多领域。此外，该项目将为培养下一代工程师和科学家提供一条途径，使他们具备在南卡罗来纳州这个新兴的技术和制造业中心从事知识密集型产业所必需的技能。PI将设计一个“原子乐高”外展活动，吸引K-12学生参与材料科学，帮助他们了解晶体和金属。该项目利用克莱姆森大学的“创造性探究”项目，让本科生，特别是女性和代表性不足的群体参与科学研究。该奖项支持中尺度理论和计算模型框架的发展，旨在促进我们对多种元素种类的晶界偏析及其在纳米晶金属合金的晶粒生长和热稳定性中的作用的基本理解。纳米晶材料由于其纳米级的晶粒尺寸，呈现出独特的组合、性能和功能。然而，在材料加工或使用条件下，晶粒生长猖獗被认为是在许多工程技术中大规模使用纳米晶金属的主要障碍之一。在本项目中，PI旨在阐明控制金属合金晶界迁移和晶粒长大的关键多元素晶界偏析机制。本项目的具体目标包括：(1)建立多组分合金中多元素晶界偏析的理论和计算相场模型，该模型考虑了块体和界面热力学，并能够模拟扩散尺度上的微观组织演变；(2)进行理论分析和计算研究，量化多元素晶界偏析对纳米晶合金热稳定性的热力学和动力学影响；(3)量化晶界网络效应在晶粒组织内溶质分配和分布中的作用。该项目位于材料科学和应用数学的交叉点，将影响材料物理学、化学热力学和纳米技术的许多领域。此外，该项目将为培养下一代工程师和科学家提供一条途径，使他们具备在南卡罗来纳州这个新兴的技术和制造业中心从事知识密集型产业所必需的技能。PI将设计一个“原子乐高”外展活动，吸引K-12学生参与材料科学，帮助他们了解晶体和金属。该项目利用克莱姆森大学的“创造性探究”项目，让本科生，特别是女性和代表性不足的群体参与科学研究。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThis award supports research and educational activities aimed at gaining fundamental insights into the segregation of multiple elemental species to grain boundaries, and how it affects grain growth in nanocrystalline metallic alloys. Nearly all functional and structural materials are polycrystalline systems; they are composed of differently oriented crystalline grains that are joined at internal interfaces, termed grain boundaries. The grain size and distribution in a metal greatly influences many engineering properties, including mechanical, thermal, and electrical. For example, the mechanical strength of a metal increases rapidly with decreasing grain size. However, due to their small grain size and high density of grain boundaries, nanocrystalline materials are usually structurally unstable. As a result, they undergo rapid grain growth, which limits their use in many technological applications. In this project, the PI will investigate the segregation of multiple types of elemental species to grain boundaries and its role in grain growth in multi-component alloys. The research involves theoretical development and numerical implementation of mathematical models that will be used to simulate the dynamics of grain boundary segregation and grain growth kinetics. A primary focus of this project will be on metallic alloys composed of three different types of elements. Lying at the intersection of materials science and applied mathematics, this project will impact numerous areas of materials physics, chemical thermodynamics, and nanotechnology. Further, this project will provide an avenue to train future-generation of engineers and scientists with the skill set necessary for careers in knowledge-intensive industries in South Carolina, which is an emerging technology and manufacturing hub. The PI will design an “Atomic Legos” outreach activity to engage K-12 students in materials science and help them learn about crystals and metals. This project leverages Clemson’s “Creative Inquiry” program in order to involve undergraduate students, particularly women and underrepresented groups, in scientific research.TECHNICAL SUMMARYThis award supports the development of a mesoscale theoretical and computational modeling framework aimed at advancing our fundamental understanding of the segregation of multiple types of elemental species to grain boundaries and its role in grain growth and thermal stability of nanocrystalline metallic alloys. Owing to their nanoscale grain size, nanocrystalline materials exhibit a unique combination and properties and functionalities. However, rampant grain growth during materials processing or under service conditions is considered one of the main hurdles to the large-scale use of nanocrystalline metals in many engineering technologies. In this project, the PI aims to elucidate key multi-element grain boundary segregation mechanisms that control grain boundary migration and grain growth in metallic alloys. Specific goals of this project include: (1) Development of a theoretical and computational phase field model of multi-element grain boundary segregation in multi-component alloys that accounts for bulk and interface thermodynamics and is able to simulate the microstructural evolution over diffusive scales; (2) Perform theoretical analysis and computational studies to quantify the thermodynamic and kinetic effects of multi-element grain boundary segregation on the thermal stability of nanocrystalline alloys; (3) Quantify the role of the grain boundary network effect in solute partitioning and distribution within grain microstructures. Lying at the intersection of materials science and applied mathematics, this project will impact numerous areas of materials physics, chemical thermodynamics, and nanotechnology. Further, this project will provide an avenue to train future-generation of engineers and scientists with the skill set necessary for careers in knowledge-intensive industries in South Carolina, which is an emerging technology and manufacturing hub. The PI will design an “Atomic Legos” outreach activity to engage K-12 students in materials science and help them learn about crystals and metals. This project leverages Clemson’s “Creative Inquiry” program in order to involve undergraduate students, particularly women and underrepresented groups, in scientific research.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.