CAREER: Understanding Nanoscale Deformation by Characterizing the Mechanical Behavior of Nanoporous Noble Metals

职业：通过表征纳米多孔贵金属的机械行为来了解纳米级变形

• 批准号: 0847693
• 负责人: Thomas Balk
• 金额: $ 40万
• 依托单位: University of Kentucky Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-12-15 至 2014-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0847693&HistoricalAwards=false
• 关键词: CAREER; Understanding; Nanoscale; Deformation; Characterizing

TECHNICAL: Nanoporous metals with nanoscale ligaments offer a unique opportunity to explore the deformation behavior of highly confined metallic volumes and understand the mechanisms that govern mechanical behavior at the nm length scale. A persistent problem exists in studies of nanocrystalline metals, thin films and nanostructured materials: what role do dislocations and other defects play in nanoscale deformation? It is understood that constraints on dislocation nucleation and motion arise as the available deformation volume decreases, but it is unclear whether dislocations are able to mediate plasticity in metal volumes that are several to tens of nm in size. Even if dislocations are involved in the deformation process, their behavior is likely to be heavily influenced by the presence of free surfaces and interfaces. Additional mechanisms such as diffusion may also occur. In order to correctly interpret and model the deformation behavior of nanocrystalline metals, we must understand the actual mechanisms that dominate deformation. The objectives of this CAREER research plan are to: (1) investigate nanoscale deformation behavior in nanoporous gold, palladium and iridium, using in situ transmission electron microscopy; (2) systematically study the mechanical properties of thin film and bulk nanoporous noble metals, and determine the appropriate scaling laws that describe these properties; (3) evaluate the damping behavior of nanoporous metals, which are expected to exhibit significantly higher damping and anelasticity versus dense or ìm-scale porous metals. The intellectual merit of this project lies in its aim to uncover the fundamental mechanisms governing the mechanical behavior of nanoporous structures. The results from this project, which will focus on face-centered cubic noble metals, should be applicable to other nanoporous metals and relevant to the study of nanoscale materials subjected to deformation. NON-TECHNICAL: This study has a strong fundamental scientific basis, but will also benefit the application of nanoporous metals by enabling improvements in their mechanical stability. Additionally, by attaining a better understanding of the mechanical behavior of nanoporous structures, fellow scientists will be able to predict and tailor properties for a given application. The broader impact of this research will enhance the undergraduate education experience for materials engineers at the University of Kentucky, by providing them with a unique opportunity to study abroad and perform research in a world-leading materials laboratory in Germany. Both graduate and undergraduate students will be directly involved in this research. The engineering student exchange program between Kentucky and Karlsruhe is a continuing focus of the PI, who will recruit UK undergraduate students to work with graduate students and with visiting German students in his laboratory. This experience will provide UK undergraduates with international exposure and help them learn how to live and work in a global society. The results of this project will be presented at conferences and disseminated in the scientific literature, with joint authorship by each team of student researchers.

技术：具有纳米级韧带的纳米多孔金属提供了一个独特的机会来探索高度受限的金属体积的变形行为，并了解控制纳米长度尺度机械行为的机制。纳米晶金属、薄膜和纳米结构材料的研究中存在一个长期存在的问题：位错和其他缺陷在纳米级变形中起什么作用？据了解，随着可用变形体积的减小，位错成核和运动受到限制，但尚不清楚位错是否能够介导尺寸为几纳米到几十纳米的金属体积的塑性。即使变形过程中涉及位错，它们的行为也可能会受到自由表面和界面的存在的严重影响。还可能发生其他机制，例如扩散。为了正确解释和模拟纳米晶金属的变形行为，我们必须了解主导变形的实际机制。该职业研究计划的目标是：（1）利用原位透射电子显微镜研究纳米多孔金、钯和铱的纳米级变形行为； （2）系统地研究薄膜和块状纳米多孔贵金属的机械性能，并确定描述这些性能的适当的标度定律； (3) 评估纳米多孔金属的阻尼行为，与致密或微米级多孔金属相比，纳米多孔金属预计会表现出明显更高的阻尼和迟弹性。该项目的智力价值在于其目的是揭示控制纳米多孔结构机械行为的基本机制。该项目的结果将重点关注面心立方贵金属，应适用于其他纳米多孔金属，并与变形纳米级材料的研究相关。非技术性：这项研究具有强大的基础科学基础，但也将通过提高纳米多孔金属的机械稳定性而有利于其应用。此外，通过更好地了解纳米多孔结构的机械行为，科学家同事将能够预测和定制特定应用的性能。这项研究的更广泛影响将增强肯塔基大学材料工程师的本科教育经验，为他们提供出国留学并在德国世界领先的材料实验室进行研究的独特机会。研究生和本科生都将直接参与这项研究。肯塔基州和卡尔斯鲁厄之间的工程学生交换计划是 PI 持续关注的重点，他将招募英国本科生在他的实验室与研究生和来访的德国学生一起工作。这种经历将为英国本科生提供国际视野，帮助他们学习如何在全球化社会中生活和工作。该项目的结果将在会议上展示并在科学文献中传播，由每个学生研究人员团队共同作者。