SGER: Electrochemical Effects on Crystal Plasticity in Nanometer-Scale Samples

SGER：电化学对纳米级样品晶体可塑性的影响

• 批准号: 0735410
• 负责人: Karl Sieradzki
• 金额: --
• 依托单位: Arizona State University
• 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: 2007-07-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0735410&HistoricalAwards=false
• 关键词: SGER; Electrochemical; Effects; Crystal; Plasticity

TECHNICAL: Recently compression testing of focused ion beam machined (FIB'd) nano-pillars have demonstrated that plastic properties such as yield strength in these large surface to volume ratio structures can approach the theoretical shear strength of a solid. These recently developed techniques offer a new experimental approach for studying environment-induced alterations of the mechanical properties of solids. This high-risk/high-payoff, transformative research program examines surface and electrochemical effects on plasticity (so-called Rehbinder effects) in FIB'd Au, Ag and Cu pillars using fundamental mechanics of materials experimental approaches combined with electrochemistry. If such an effect is discovered, it would be transformative in the sense that a new paradigm for understanding stress-corrosion phenomena would emerge. PI's study uses two experimental protocols. One involves the development of a new technique for examining the compressive behavior of essentially dislocation-free 200 nm diameter metallic pillars in an electrochemical cell. The other involves the use of wafer curvature techniques to ascertain surface stress changes in electrolytes owing to the adsorption of underpotentially deposited ad-layers. The important and practical problems addressed in this research deal with outstanding fundamental issues related to plasticity and environmental effects on mechanics of materials at small length scales. These chemical/mechanical effects have been notoriously difficult to study and consequently many researchers have questioned the very existence of these phenomena. With the advent of nano-technology, these issues are once again at the forefront of interesting and unsolved problems in the mechanics of materials. NON-TECHNICAL: If PI demonstrates that surface stress alterations affect surface dislocation nucleation, this finding would impact broader understanding of the ductile versus brittle response of a crack in a solid. Thus this research would provide researchers a new "knob to turn" in order to control the deformation and fracture properties of a solid. Consequently new classes of structural materials may have the potential to be "tuned" for immunity to stress-corrosion failure. Expertise in chemical effects on the mechanics of materials requires the ability to integrate knowledge in the disciplines of electrochemistry, applied mechanics and materials science. PI is developing a new undergraduate course in this area that will be taught at the senior undergraduate level specifically aimed at providing students with this integrated background. Additionally, the PI will be involving undergraduate students in this research through Arizona State University's NSF funded Minority Graduate Education @ Mountain State Alliance (MGE@MSA) program.

技术支持：最近，聚焦离子束加工（FIB'd）纳米柱的压缩测试已经证明，这些大的表面与体积比结构中的塑性性质（诸如屈服强度）可以接近固体的理论剪切强度。这些最近发展起来的技术为研究环境引起的固体力学性质的改变提供了一种新的实验方法。这个高风险/高回报，变革性的研究计划研究表面和电化学对FIB的Au，Ag和Cu柱塑性的影响（所谓的粘合剂效应），使用材料实验方法结合电化学的基本力学。如果发现这种效应，它将是变革性的，在这个意义上，一个新的范式来理解应力腐蚀现象将出现。PI的研究使用了两种实验方案。其中之一涉及开发一种新技术，用于检查电化学电池中基本无位错的200纳米直径金属柱的压缩行为。另一个涉及使用晶片曲率技术，以确定由于吸附的潜在沉积广告层的电解质表面应力的变化。在这项研究中解决的重要和实际的问题处理有关的塑性和环境对小长度尺度材料力学的影响突出的基本问题。众所周知，这些化学/机械效应很难研究，因此许多研究人员质疑这些现象的存在。随着纳米技术的出现，这些问题再次成为材料力学中有趣且未解决的问题的前沿。非技术性：如果PI表明，表面应力的变化影响表面位错成核，这一发现将影响更广泛的理解的韧性与脆性的裂纹在固体中的响应。因此，这项研究将为研究人员提供一个新的“旋钮”，以控制固体的变形和断裂性能。因此，新型结构材料可能有可能被“调整”以免受应力腐蚀失效的影响。在材料力学的化学效应的专业知识需要在电化学，应用力学和材料科学的学科知识整合的能力。PI正在开发一个新的本科课程，在这方面，将在高级本科水平专门为学生提供这种综合背景授课。此外，PI将通过亚利桑那州立大学的NSF资助的少数民族研究生教育@山区国家联盟（MGE@MSA）计划，让本科生参与这项研究。