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：最近对聚焦离子束加工（FIB'D）纳米柱进行压缩测试，证明了这些较大的表面与体积比结构中的塑料特性，例如屈服强度，可以接近固体的理论剪切强度。这些最近开发的技术提供了一种新的实验方法，用于研究固体机械性能的环境诱导的改变。这项高风险/高付费的变革性研究计划使用材料实验方法的基本力学与电化学相结合，研究了纤维，Ag和Cu支柱对可塑性（所谓的Rehbinder效应）的表面和电化学作用。如果发现这种影响，那将是一种变革性的，从某种意义上说，将出现一种新的范式来理解压力腐败现象。 PI的研究使用了两个实验方案。其中一种涉及开发一种新技术，用于检查电化学细胞中基本无位错200 nm金属柱的压缩行为。另一个涉及使用晶圆曲率技术来确定由于电位不足的ad层的吸附而确定电解质的表面应力变化。这项研究中解决的重要和实用问题涉及与较小尺度的材料力学有关的可塑性和环境影响有关的杰出基本问题。众所周知，这些化学/机械作用很难研究，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，这些问题再次处于材料机制中有趣且未解决的问题的最前沿。非技术：如果PI证明表面应力改变会影响表面脱位成核，则该发现将影响对固体中裂纹的延性和脆性反应的更广泛理解。因此，这项研究将为研究人员提供一个新的“转动旋钮”，以控制固体的变形和断裂特性。因此，新的结构材料可能具有“调整”的潜力，以免疫应激腐蚀失败。化学作用对材料力学的专业知识需要在电化学，应用力学和材料科学的学科中整合知识的能力。 PI正在该领域开发一门新的本科课程，该课程将在高级本科级别教授，专门为学生提供这种综合背景。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 @ Mountain State Alliance（MGE @ MSA）计划参与本科生的本科生。