Effect of Grain Boundary and Size on Electro-Thermo-Mechanical Properties and Internal Friction of Nano Grained Thin Metal Films Using MEMS Devices

目的：我们的第一个目标是首次使用MEMS传感器和致动器测量独立纳米颗粒纳米金属薄膜的以下特性：(a)由于单轴载荷引起的弹性和塑性响应，(b)电导率，(c)导热性，以及(d)在低温到高温和各种机械应力下的内摩擦。我们的第二个目标是探索晶界和表面在确定测量性质中的作用。例如，与晶粒内的原子相比，已知晶界原子是随机和稀疏排列的。我们将研究晶界是否提供足够的顺应性（与晶界滑动的机制相反），以降低纳米颗粒金属的弹性模量，与它们的体相比较（在我们的初步实验中观察到）。同样，我们将探讨丰富的晶界是否会引起传导（电和热）电子的充分散射，从而增加热电电阻。将发展理论模型来解释和预测纳米尺度金属的热电机械性能。这些模型将考虑到晶界和表面。教育：研究和教育必须相辅相成。研究推进知识的前沿，而教育传播知识。作为PI的CAREER项目（1998年获奖）的一部分，MEMS视频系列已经为广泛的受众开发，包括高中生和中学生以及对MEMS感兴趣的基础科学背景的人。该系列题为“微机械世界之旅”，可在http://www.mie.uiuc.edu.The上获得，该项目的教育部分将包括：(A)开发关于纳米材料和技术的短视频系列，以及用于测试这些看不见的样品的微型仪器。本项目将招收不同群体的本科生研究助理；(b)开发网页，通过实验视频和动画的形式发布纳米材料的新发现（以澄清概念）；(c)为大四学生和研究生开发纳米材料研究新方法的新课程；(d)在材料力学、设计等机械工程传统课程中引入纳米材料的行为主题。伊利诺伊大学为学生举办夏令营。纳米技术的概念将通过PI的实验室参观，视频系列和非正式讨论向来访的年轻观众介绍。

Objective: Our first goal is to measure, for the first time, using MEMS sensors and actuators, the following properties of free standing nano grained nano scale metal films:(a) elastic and plastic response due to uniaxial loading, (b) electrical conductivity, (c) thermal conductivity, and (d) internal friction in low to high temperatures and under various mechanical stresses. Our second goal is to explore the role of grain boundaries and the surfaces in determining the measured properties. For example, grain boundary atoms are known to be randomly and sparsely arranged compared to those within the grains. We will investigate whether the grain boundaries offer sufficient compliance (in contrast to the mechanism of grain boundary sliding) to nano-grained metals lowering the elastic modulus compared to their bulk counterparts (observed in our preliminary experiments). Similarly, we will explore whether the abundant grain boundaries may cause sufficient scattering of the conduction (electrical and thermal) electrons, thus increasing thermo-electric resistively. Theoretical models will be developed to explain and predict the thermo electro mechanical properties of nano scale metals.The models will account for grain boundaries and surfaces.Education: Research and education must be complementary to each other. Research advances the frontier of knowledge, whereas education disseminates it. As part of PI 's CAREER project (awarded 1998), video series on MEMS has been developed for broad audience including high and middle school students and people with basic science background interested in MEMS. The series, titled A voyage through the world of micromachine is available at http://www.mie.uiuc.edu.The education component of the this project will include:(a) development of short video series onnano materials and technology ,and the micro instruments for testing such invisible samples. Undergraduate research assistants from diverse group will be recruited for this project; (b) development of web page where micro instruments will be highlighted as well as new findings on nano materials will be posted through videos of experiments and animations (to clarify concepts),(c)development of new course for seniors and entering graduate students on new methods of studying materials at nano scale, (d)introduction of the topic of nano scale materials 'behavior in the traditional courses of mechanical engineering such s mechanics of materials, and design. University of Illinois hosts summer camps for school students. The concepts of nanotechnology will be presented to the visiting young audience through PI 's lab tour, the video series and informal discussions.