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; 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：带有纳米级韧带的纳米多孔金属为探索高度受限金属量的变形行为提供了独特的机会，并了解在NM长度尺度上控制机械行为的机制。纳米晶金属，薄膜和纳米结构材料的研究中存在一个持续的问题：纳米级变形中的脱位和其他缺陷在什么作用和其他缺陷中起什么作用？可以理解，随着可用的变形体积的下降，对位错成核和运动的约束会产生，但是尚不清楚位错是否能够介导金属体积的可塑性，而金属体积的大小为几个至nm。即使错位参与变形过程，它们的行为也可能受到自由表面和接口的存在的严重影响。还可能发生其他机制，例如扩散。为了正确解释和建模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）使用原位传输电子显微镜研究纳米孔黄金，钯和虹膜的纳米级变形行为； （2）系统地研究薄膜和大量纳米多孔贵金属的机械性能，并确定描述这些特性的适当缩放定律； （3）评估纳米孔金属的阻尼行为，预计纳米孔金属有效地更高的阻尼和弹性性与密度或M级多孔金属。该项目的智力优点在于它的目的是揭示纳米孔结构机械行为的基本机制。该项目的结果将集中在以面部为中心的立方贵族金属上，应适用于其他纳米多孔金属，并与对经历变形的纳米级材料的研究有关。非技术性：这项研究具有强大的基本科学基础，但也将通过改善其机械稳定性来使纳米孔金属的应用受益。此外，通过更好地了解纳米多孔结构的机械行为，科学家将能够预测和量身定制给定应用的特性。这项研究的更广泛影响将通过为肯塔基大学的材料工程师的本科教育经验提供了一个独特的机会，可以在德国的世界领先的材料实验室中留学和进行研究。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（Karlsruhe）之间的工程学生交流计划是PI的持续重点，PI将招募英国本科生与研究生一起工作，并与他的实验室中的德国学生一起工作。这种经验将为英国大学生提供国际曝光，并帮助他们学习如何在全球社会中生活和工作。该项目的结果将在会议上呈现，并在科学文献中传播，并由每个学生研究人员共同作家。