EAGER: Probing Deformation Mechanism Transition of Metals at the Nanoscale

技术综述：该项目的研究目标是在纳米尺度上探索金属力学行为中最重要的问题之一，即从位错相互作用控制区向表面位错成核区转变的塑性机制的存在的实验验证。具体的技术目标是将最近开发的原位微机械纳米压痕阶段集成在扫描电子显微镜和透射电子显微镜中。这将被用来系统地高分辨率定量研究尺寸可控的高质量单晶金、银、铜和镍纳米线的变形。除了几何尺寸效应外，还将研究应变率和温度的作用。非技术摘要：金属变形机制的研究对冶金领域的发展至关重要。随着最近纳米技术的出现和实验技术的进步，在纳米尺度上研究金属的变形机制变得既具有技术意义又具有重要的科学意义。这项工作的成功实施将有助于阐明金属中从位错交互作用控制塑性到表面位错成核控制塑性的重要转变。在不同加载速率和温度下进行的研究将提供关于纳米尺度金属塑性动力学方面的有价值的信息。这项热切的提议的教育目标是激励学生在科学和工程领域追求成功的职业生涯。这将通过将拟议的研究工作与一系列教育和外联努力相结合来实现，包括为莱斯大学的本科生创建创新的实验室模块，指导不具代表性的本科生以及当地高中教师和学生的暑期研究经验。

TECHNICAL SUMMARY: The research goal of this EAGER project is to probe one of the most important problems on the mechanical behavior of metals at the nanoscale, namely experimental verification of the existence of a mechanism of plasticity involving the transition from a dislocation interaction controlled regime to a surface dislocation nucleation dominated regime. The specific technical objectives are to integrate recently developed in situ micro-mechanical nanoindentation stages in both the SEM and TEM. These will be used for systematic high-resolution quantitative investigations of the deformation of high-quality single crystalline Au, Ag, Cu and Ni nanowires with well-controlled dimensions. In addition to geometrical size effects, the roles of strain rate and temperature will also be investigated.NON-TECHNICAL SUMMARY: The study of deformation mechanisms in metals has been of paramount importance in developing the field of metallurgy. With the recent emergence of nanotechnology and the advancement of experimental techniques, investigating the deformation mechanism of metals at the nanoscale has become both technologically relevant and scientifically important. The successful implementation of the proposed work will help elucidate the important transitions from dislocation-interaction-controlled-plasticity to surface-dislocation-nucleation-controlled plasticity in metals. The studies carried out at different loading rates and temperatures will provide valuable information on kinetic aspects of metal plasticity at the nanoscale. The educational goal of this EAGER proposal is to inspire students to pursue successful careers in science and engineering fields. This will be done by integrating the proposed research work with a number of educational and outreach efforts, including creating innovative lab modules for undergraduate students at Rice, mentoring under-representative undergraduate students and local high school teachers and students for summer research experiences.