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传感器和致动器来测量自支撑纳米颗粒金属薄膜的下列特性：(A)单轴加载下的弹性和塑性响应；(B)导电性；(C)导热性；(D)在低温、高温和各种机械应力下的内耗。我们的第二个目标是探索晶界和表面在决定测量特性中的作用。例如，与颗粒内的原子相比，晶界原子的排列是随机和稀疏的。我们将调查晶界是否提供了足够的顺应性(与晶界滑动的机制相反)，以降低纳米晶金属的弹性模量(在我们的初步实验中观察到)。类似地，我们将探索丰富的晶界是否会导致传导(电和热)电子的充分散射，从而增加热电阻率。将开发理论模型来解释和预测纳米金属的热电机械性能。这些模型将考虑晶界和表面。教育：研究和教育必须相辅相成。研究推进了知识的前沿，而教育则传播了知识。作为皮S职业生涯项目(1998年获奖)的一部分，有关MEMS的系列视频已经被广泛地面向广大受众，包括对MEMS感兴趣的高中生和具有基础科学背景的人。这一名为《微机械世界之旅》的系列可在http://www.mie.uiuc.edu.The教育部门获得，该项目将包括：(A)开发短视频系列波拿诺材料和技术，以及用于测试这种隐形样品的微型仪器。该项目将招募来自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发布关于纳米材料的新发现以及微型仪器的新发现(以澄清概念)，(C)为高年级学生开发新的课程，让研究生学习纳米尺度材料的新方法，(D)在S材料力学和设计等传统机械工程课程中介绍纳米材料的行为主题。伊利诺伊大学为在校学生举办夏令营。纳米技术的概念将通过皮·S实验室之旅、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.