Experiments and Models on Room Temperature Creep of Nanocrystalline Metallic Films

纳米晶金属薄膜室温蠕变实验与模型

• 批准号: 0927149
• 负责人: Ioannis Chasiotis
• 金额: $ 39.85万
• 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: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0927149&HistoricalAwards=false
• 关键词: Experiments; Models; Room; Temperature; Creep

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This research project integrates experiments and modeling to develop physics-based predictive models for the problem of room temperature creep in nanocrystalline metallic films. The novel experiments aim at extracting directly the grain-boundary (GB) sliding viscosity and the GB diffusivity. Model experiments augmented with atomic force microscopy measurements will obtain the displacement jumps as a function of time. The measured local GB parameters will be incorporated in cohesive models for the GBs in a multiscale model for polycrystalline Au to quantify the effect of inelastic GB mechanisms on the creep response of nanocrystalline Au films. While other homogenization schemes use the macroscale material behavior to fit microscale parameters, the proposed multiscale experimental/modeling protocol employs macroscale experiments to validate the multiscale modeling predictions.This project can have significant technological and educational impacts. Several thin film applications, such as radio frequency microelectromechanical systems, variable capacitors and tunable filters involve fixed-fixed metal structures that suffer from loss of mechanical stiffness due to creep at room temperature. Quantification of the GB mechanisms in nanocrystalline metals will allow for mitigating strategies to prevent room temperature creep but maintain the high yield strength that is controlled by dislocation crystal plasticity. Once perfected, the experiments will be integrated in the PI's experimental course "Nanoscale Contact Mechanics" that provides theoretical and experimental education and training to graduate students by following a "bottom-up" methodology in mechanics.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。该研究项目将实验和建模相结合，为纳米晶金属薄膜的室温蠕变问题开发基于物理的预测模型。新的实验旨在直接提取晶界（GB）滑动粘度和GB扩散率。用原子力显微镜测量增强的模型实验将获得作为时间的函数的位移跳跃。所测得的本地GB参数将被纳入凝聚力模型中的GB多晶Au的多尺度模型，以量化非弹性GB机制的纳米晶Au膜的蠕变响应的影响。虽然其他均匀化方案使用宏观尺度材料行为来拟合微观尺度参数，但所提出的多尺度实验/建模协议使用宏观尺度实验来验证多尺度建模预测。几种薄膜应用，如射频微机电系统、可变电容器和可调谐滤波器，涉及固定-固定金属结构，其在室温下由于蠕变而遭受机械刚度损失。纳米晶金属中GB机制的量化将允许缓解策略，以防止室温蠕变，但保持由位错晶体塑性控制的高屈服强度。一旦完善，这些实验将被整合到PI的实验课程“纳米接触力学”中，该课程通过遵循力学中的“自下而上”方法，为研究生提供理论和实验教育和培训。