EAGER: Oxide Film Effects on Dislocation Nucleation -- Implications to Structure/Property Relations

EAGER：氧化膜对位错成核的影响——对结构/性能关系的影响

• 批准号: 0946337
• 负责人: William Gerberich
• 金额: $ 26.44万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-12-15 至 2012-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0946337&HistoricalAwards=false
• 关键词: EAGER; Oxide; Film; Effects; Dislocation

TECHNICAL SUMMARYThis project involves a combination of in situ nanoindentation studies in a Transmission Electron Microsocpe (TEM) with in situ measurements of electrical conductance between tip and sample. It is now possible to measure small conductance changes induced by dislocation nucleation, while simultaneously measuring nanoindentation curves. This powerful measurement capability will address the role of native oxide film formation on nanoscale mechanical properties. This effect is very important because as sizes scale downwards, the oxide role is inadequately understood but of relevance to a large variety of technological issues such as stress corrosion cracking, fretting fatigue, mechanically-assisted dielectric breakdown, fatigue of Micro-Electro-Mechanical Systems (MEMS), fracture toughness of nanostructures, MEMS tribology and wear and yielding in general. Model thin-film systems comprised of metal or semiconductor films coated with oxide overlayers will be used to explore fundamentals of the early stages of dislocation nucleation at or near surfaces, i.e. to establish the critical structure-property relationships at the nanometer scale. In particular, understanding the indentation size effect at very small length scales is unresolved in most metallic systems since the image forces associated with native oxide films have usually been ignored. By measuring conductive contacts during deformation of oxide-covered thin metallic films, simultaneously with load-displacement output, dislocation scale events can be directly monitored.NON-TECHNICAL SUMMARYThe proposed work has the potential to impact an unusually wide range of scientific communities because it is fundamentally inter-disciplinary. It includes instrumental, scientific, and technological advances that will be of interest to the communities doing research on electron microscopy, electronic transport in nanostructures and atomistic simulation of mechanical properties of materials. The proposed research is of very significant value technologically. Oxide film formation affects mechanical properties at small length scales and plays and important role in areas as diverse as stress corrosion cracking, fretting fatigue, mechanically assisted dielectric breakdown, fatigue of MEMS, fracture toughness of nanostructures, MEMS tribology and wear. These are core issues in many areas of nanotechnology that will be immediately impacted by the proposed research. The PIs have an excellent record of inclusion of undergraduate students in their research, an effort that will be aggressively continued during the duration of this award. These students are funded through various programs such as the UMN Undergraduate Research Opportunities Program, NSF REU programs, directed research for credit, etc., and have been involved in all aspects of the activities of the PI?s research groups.

技术总结本项目包括在透射电子显微镜（TEM）中的原位纳米压痕研究与尖端和样品之间的电导率的原位测量相结合。现在可以测量位错成核引起的小电导变化，同时测量纳米压痕曲线。这种强大的测量能力将解决自然氧化膜形成对纳米级机械性能的作用。这种效应是非常重要的，因为随着尺寸的缩小，氧化物的作用还没有得到充分的理解，但与各种各样的技术问题有关，例如应力腐蚀开裂、微动疲劳、机械辅助介电击穿、微机电系统（MEMS）的疲劳、纳米结构的断裂韧性、MEMS摩擦学以及磨损和屈服。模型薄膜系统由金属或半导体薄膜覆盖氧化物覆盖层将被用来探索的位错成核的早期阶段的基本面或附近的表面，即建立在纳米尺度的关键结构-性能关系。特别是，理解在非常小的长度尺度的压痕尺寸效应是未解决的，在大多数金属系统，因为与自然氧化膜的图像力通常被忽略。通过测量氧化物覆盖的金属薄膜变形期间的导电接触，同时输出载荷-位移，可以直接监测位错尺度事件。非技术总结拟议的工作有可能影响异常广泛的科学界，因为它从根本上来说是跨学科的。它包括仪器，科学和技术的进步，这将是感兴趣的社区做电子显微镜，电子输运纳米结构和原子模拟材料的机械性能的研究。该研究具有重要的技术价值。氧化膜的形成影响小长度尺度的机械性能，并在应力腐蚀开裂、微动疲劳、机械辅助介电击穿、MEMS疲劳、纳米结构断裂韧性、MEMS摩擦学和磨损等领域发挥重要作用。这些是纳米技术许多领域的核心问题，将立即受到拟议研究的影响。PI在本科生参与研究方面有着出色的记录，这一努力将在本奖项颁发期间积极继续。这些学生通过各种项目获得资助，如UMN本科生研究机会项目，NSF REU项目，信贷指导研究等，并参与了PI活动的各个方面？的研究小组。