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) 纳米柱的压缩测试表明，这些大表面积与体积比结构中的塑性特性（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为研究环境引起的固体机械性能的变化提供了一种新的实验方法。这项高风险/高回报的变革性研究计划利用基本材料力学实验方法与电化学相结合，研究 FIB 的金、银和铜柱中可塑性的表面和电化学效应（所谓的 Rehbinder 效应）。如果发现这种效应，那么从某种意义上说，这将是变革性的，将会出现一种理解应力腐蚀现象的新范式。 PI 的研究使用了两种实验方案。其中一项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 nm 直径金属柱的压缩行为。另一种涉及使用晶片曲率技术来确定由于吸附电位不足的沉积广告层而引起的电解质表面应力变化。这项研究解决的重要和实际问题涉及与小长度尺度材料力学的塑性和环境影响相关的突出基本问题。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尚未解决的问题的前沿。非技术性：如果 PI 证明表面应力变化会影响表面位错成核，那么这一发现将影响对固体裂纹的延性与脆性响应的更广泛理解。因此，这项研究将为研究人员提供一种新的“转动旋钮”，以控制固体的变形和断裂特性。因此，新型结构材料可能具有“调整”以抵抗应力腐蚀失效的潜力。材料力学化学效应方面的专业知识需要具备整合电化学、应用力学和材料科学学科知识的能力。 PI 正在该领域开发一门新的本科课程，该课程将在本科高年级教授，专门旨在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 NSF 资助的少数民族研究生教育 @ 山地联盟 (MGE@MSA) 项目让本科生参与这项研究。