Interplay Between In-Homogeneity and Size Scale of Microstructure: A New Paradigm in the Mechanistic Exploration of Nano Grained Metal Deformation

微观结构不均匀性与尺寸尺度之间的相互作用：纳米晶粒金属变形机理探索的新范式

• 批准号: 0728189
• 负责人: Taher Saif
• 金额: $ 33.5万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0728189&HistoricalAwards=false
• 关键词: Interplay; Between; Homogeneity; Size; Scale

Intellectual merit: We have experimental evidence showing that plastically deformed polycrystalline free standing thin metal films with average grain size of 50-100nm recover all of the plastic strain under macroscopic stress-free condition (Science, (2007) 315, pp 1831-34). This observation challenges the age-old view that plastic strain is permanent. When the grain size is increased to 100-200nm, the films do not recover plastic strain, but they show strong Bauschinger effect during unloading, while still under tension. These surprising and seemingly unrelated phenomena, we hypothesize, are governed by an interplay between the small size scale of the microstructure and its inhomogeneity (grain size and orientation variations). This project will explore this relatively unexplored paradigm. It will investigate the mechanism of strain recovery and Bauschinger effect in thin metal films (Al, Cu, Au and Ni) through quantitative in-situ deformation and annealing studies of thin metal films in Transmission Electron Microscope (TEM) using a novel MEMS based testing stage. The work will be conducted jointly with Austrian Academy of Science.Broader impact: The insight gained from the project will be essential to develop computional/theoretical models of nanomaterials. The students involved in the project will have the rare opportunity to travel to Austria and work with international scientists. The research will be integrated with education in two new ways: (1) groups of undergraduate students will develop short videos on nanomaterials; (2) Two faculty members and 4 students from Cal Poly (a teaching college) will be trained on nano materials during summer breaks. The research is co-funded by the Office of International Science and Engineering (OISE) and the Engineering Directorate Materials Processing and Manufacturing Program (ENG/CMMI/MPM

智力优点：我们有实验证据表明，塑料变形的多晶型薄金属膜，平均晶粒大小为50-100nm，在宏观应力的条件下恢复了所有塑性应变（Science，（Science，（2007）315，PP 1831-34）。该观察结果挑战了塑性应变是永久性的古老观点。当晶粒尺寸增加到100-200nm时，膜不会恢复塑性应变，但是在卸载过程中它们仍表现出很强的鲍申格效应，同时仍处于紧张状态。我们假设这些令人惊讶且看似无关的现象受微观结构的小尺寸尺度及其不均匀性（晶粒尺寸和方向变化）之间的相互作用。该项目将探索这个相对未开发的范式。它将通过使用新型MEMS基于MEMS的测试阶段进行定量的原位变形和薄金属膜对薄金属膜对薄金属膜对薄金属膜的定量现场变形和退火研究来研究应变恢复和Bauschinger效应的机制。这项工作将与奥地利科学学院共同开展。Boader的影响：从项目中获得的见解对于开发纳米​​材料的构成/理论模型至关重要。参与该项目的学生将有难得的机会前往奥地利并与国际科学家合作。该研究将通过两种新的方式与教育融合：（1）一组本科生将在纳米材料上制作简短的视频； （2）在夏季假期期间，将对来自Cal Poly的两名教职员工和4名学生（教学学院）接受纳米材料的培训。 该研究由国际科学与工程办公室（OISE）和工程局材料处理和制造计划（ENG/CMMI/MPM）共同资助