CAREER: Nanocrystalline Grain Boundary Network Engineering Enabled by New Deformation Mechanisms

技术总结：该职业奖支持一个研究项目，该项目旨在揭示纳米晶晶界网络在塑性变形过程中如何演变，并了解这种演变如何影响后续的机械响应。人们假设，纳米金属独特的形变物理将允许通过热机械处理来操纵晶界网络，将晶界工程和纳米结构材料这两个迄今分离的领域联系起来。具体地说，这项研究是由三个技术目标驱动的：(1)表征纳米材料中晶界网络的细节，(2)测量在热机械循环下晶界特征分布和网络拓扑的演变，以及(3)利用所获得的洞察力来开发将晶界网络细节与力学行为联系起来的新材料理论。这项工作将结合先进的表征技术、精心设计的机械测试和原子模拟来实现这些目标。本文所获得的见解将用于将界面网络特性与纳米晶体的力学行为联系起来，并优化纳米结构材料的界面设计。非技术概述：该计划是由几个与技术相关的问题推动的：(1)纳米结构材料的性能如何受到其晶界网络细节的影响？(2)在室温和高温下的机械变形如何改变这些界面网络？(3)是否可以通过热机械处理来优化晶界网络，以设计出更好的纳米材料？这项工作将为控制晶界结构的细节和所有晶界形成的互连网络提供路线图，以创造改进的纳米结构材料和实现下一代技术。此外，该项目还支持一项外联计划，以扩大代表不足的少数民族和妇女在科学、技术、工程和数学(STEM)领域的参与。将实施一种多层次的方法，通过直接的实验室经验和接触跨学科研究，吸引高中生和教师以及本科生并增强他们的能力。

TECHNICAL SUMMARY:This CAREER award supports a research project to reveal how nanocrystalline grain boundary networks evolve during plastic deformation and understand how this evolution affects subsequent mechanical response. It is hypothesized that the unique deformation physics of nanocrystalline metals will allow for manipulation of the grain boundary network through thermomechanical treatments, connecting the heretofore separate fields of grain boundary engineering and nanostructured materials. Specifically, the research is driven by three technical objectives: (1) characterize the details of the grain boundary network in nanocrystalline materials, (2) measure the evolution of grain boundary character distribution and network topology under thermomechanical cycling, and (3) leverage the insight gained to develop new materials theory which connects grain boundary network details to mechanical behavior. This work will combine advanced characterization techniques, carefully designed mechanical testing, and atomistic simulations to meet these objectives. The insights obtained here will be used to connect interfacial network character to nanocrystalline mechanical behavior and to optimize the design of interfaces in nanostructured materials.NON-TECHNICAL SUMMARY:This program is motivated by several technologically relevant questions: (1) How are the properties of nanostructured materials influenced by the details of their grain boundary networks? (2) How does mechanical deformation, both at room and elevated temperatures, alter these interfacial networks? (3) Can the grain boundary network be optimized, through thermomechanical treatments, to engineer better nanomaterials? This work will provide a roadmap for controlling the details of grain boundary structure and the interconnecting network formed by all boundaries in order to create improved nanostructured materials and enable next-generation technologies. In addition, this project supports an outreach program to broaden the participation of underrepresented minorities and women in Science, Technology, Engineering, and Mathematics (STEM) fields. A multi-tiered approach will be implemented to engage and empower high school students and teachers, as well as undergraduate university students, through direct laboratory experiences and exposure to interdisciplinary research.