Investigation of High Strain-Rate Deformation and Failure of FCC and BCC Nanostructures

FCC 和 BCC 纳米结构的高应变率变形和失效研究

• 批准号: 1408901
• 负责人: Horacio Espinosa
• 金额: $ 42万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-15 至 2020-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1408901&HistoricalAwards=false
• 关键词: Investigation; Strain; Rate; Deformation; Failure

NON-TECHNICAL DESCRIPTION: Nanostructures such as nanowires and nanotubes are envisioned to play a critical role in the next generation of advanced materials for energy, electronic devices, and nano-electromechanical systems. This broad technological applicability has elicited a demand for extensive characterization of the fundamental properties of nanostructures, yet previous studies have neglected to characterize these materials under high strain-rate conditions. This project involves characterizing the mechanical properties of metallic nanowires at high strain rates using transmission electron microscopy and developing new theoretical models to understand the relationship between the structure of the nanowires and their mechanical properties. This fundamental research provides opportunities to develop new educational modules on the subject of mechanical properties testing and stimulates new innovations in the design and manufacture of high performing robust nanoscale devices. As well, training of a graduate student and post-doctoral associate is an inherent part of this research.TECHNICAL DETAILS: The goal of this research project is to explore for the first time the mechanical response of sub-150 nm-diameter metallic nanowires at high strain rates (up to 10^5 /s) to elucidate the structure-property relationships of nanostructures at high strain rates. To this end, nanowires are experimentally characterized by augmenting microelectromechanical systems (MEMS) mechanical characterization platforms with capabilities for in situ transmission electron microscopy (TEM) testing. The newly designed MEMS platforms with piezoelectric-based actuation and reduced mass are designed to attain strain rates up to 10^5/s. This testing is coupled to dynamic, high-speed TEM (DTEM) in order to obtain high speed imaging of the deformation and failure processes. These state-of the-art experimental techniques yield significant insights toward the understanding of high-strain rate mechanical behavior of metallic nanowires, dislocation processes in confined geometries, and validation of interatomic potentials for molecular dynamics (MD)-based modeling of metals. This validation is extremely beneficial to atomistic modeling, not only for mechanical characterization, but for a breadth of scientific disciplines where MD simulations are used to gain insights into chemical, electrical, and thermal material behavior.

非技术描述：预计纳米线和纳米管等纳米结构将在下一代能源、电子设备和纳米机电系统先进材料中发挥关键作用。这种广泛的技术适用性引发了对纳米结构基本特性进行广泛表征的需求，但之前的研究忽略了在高应变率条件下表征这些材料。该项目涉及使用透射电子显微镜表征金属纳米线在高应变率下的机械性能，并开发新的理论模型以了解纳米线的结构与其机械性能之间的关系。这项基础研究为开发有关机械性能测试的新教育模块提供了机会，并激发了高性能稳健纳米级设备设计和制造的新创新。 此外，对研究生和博士后的培训也是本研究的固有组成部分。 技术细节：本研究项目的目标是首次探索亚 150 nm 直径金属纳米线在高应变率（高达 10^5 /s）下的机械响应，以阐明纳米结构在高应变率下的结构-性能关系。为此，通过增强具有原位透射电子显微镜 (TEM) 测试功能的微机电系统 (MEMS) 机械表征平台来对纳米线进行实验表征。新设计的 MEMS 平台采用基于压电的驱动和减少的质量，旨在实现高达 10^5/s 的应变率。该测试与动态高速 TEM (DTEM) 相结合，以获得变形和失效过程的高速成像。这些最先进的实验技术为理解金属纳米线的高应变率机械行为、受限几何形状中的位错过程以及基于分子动力学 (MD) 的金属建模的原子间势的验证提供了重要的见解。这种验证对于原子建模极其有益，不仅适用于机械表征，而且适用于使用分子动力学模拟来深入了解化学、电气和热材料行为的广泛科学学科。