Nanomechanics of Tough Nanostructured Metals

纳米结构金属，其微观结构长度尺度通常小于100纳米，是近年来大量研究的主题。它们在结构上以大量的内部界面为特征，如晶界或孪晶界，这可能会显著改变它们的物理、机械和化学性能。在典型的纳米结构金属中，强度和延展性之间往往存在令人遗憾的权衡。纳米晶金属通常表现出比传统粗粒金属高5倍的强度。但它们的延展性往往很差，从而限制了它们的结构甚至功能应用。提出的研究目标是为设计具有超高强度和高延性的韧性纳米结构材料开发一个强大的建模和实验框架。本文将以纳米结构铜为模型系统，通过紧密耦合的建模和实验研究，阐明纳米结构金属延性控制的主动机制，并为生产坚韧的纳米结构材料开发新的加工方法。这项研究将通过对纳米结构金属信息机制的理解取得根本性的进步，从而产生更广泛的影响。这项研究是工程设计坚韧纳米结构材料的必要的第一步，这可能会导致微系统应用中显著的重量和能源节约。纳米结构材料的新型变形机制和加工技术的知识将被整合到本科高级课程中。本项目将招收少数民族本科生进行暑期研究。我们提供这些机会来激发他们在纳米科学和纳米技术领域追求事业的兴趣。

Nanostructured metals, with microstructural length scales typically smaller than 100 nm, have been the subject of considerable research in recent years. They are structurally characterized by a large number of internal interfaces such as grain boundaries or twin boundaries, which may significantly change their physical, mechanical, and chemical properties compared to the coarse-grained counterparts. In typical nanostructured metals, there is often a regrettable trade-off between strength and ductility. Nanocrystalline metals routinely exhibit up to five times higher strength than conventional coarse-grain metals. But their ductilities are often poor, thus limiting their structural and even functional applications. The goal of the proposed research is to develop a robust modeling and experimental framework for the design of tough nanostructured materials of ultrahigh strength and high ductility. Taking the nanostructured copper as a model system, a tightly coupled modeling and experimental study will be performed to elucidate the active mechanisms controlling ductility in nanostructured metals, and to develop novel processing methods for producing tough nanostructured materials. This research will achieve a broader impact through a fundamental advancement in the understanding of information mechanisms in nanostructured metals. The proposed research is the necessary first step toward engineering tough nanostructured materials which may lead to significant weight and energy savings in applications of microsystems. The knowledge of novel deformation mechanisms and processing techniques of nanostructured materials will be integrated into the senior undergraduate course. Minority undergraduates will be recruited for summer research on this project. We offer these opportunities to inspire their interests in pursuing the career in the area of nanoscience and nanotechnology.