The Properties and Behaviors of Grain Boundaries in Fine Structures

精细结构中晶界的性质和行为

• 批准号: 9530314
• 负责人: Alexander King
• 金额: $ 50.13万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-07-01 至 2000-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9530314&HistoricalAwards=false
• 关键词: Properties; Behaviors; Grain; Boundaries; Fine

9530314 King This project combines theory and experiment in a study of the effects of free surfaces and triple junctions upon grain boundary structure, properties and behavior. Traditional approaches to grain boundary properties rely on models that are intrinsically infinite, and relatively little attention has been paid to the effects associated with the non-infinite extent of real interfaces. Calculations are made of the elastic fields of grain boundaries made up of dislocation arrays in finite materials, taking into account surface relaxation effects. The effects of free surfaces on the dislocations are considered with a view towards understanding how dislocations are eliminated from grain boundaries, resulting in changes of misorientation. These effects are also studied in polycrystalline films using in-situ transmission electron microscopy experiments which are compared to the calculations. The project includes a study of the properties and behavior of triple junctions within polycrystalline materials. For certain classes of materials, notably thin films, triple junctions may fall into restricted symmetry classes in which the anisotropy of the grain boundary energy exerts a controlling influence on the morphology of the triple line. An attempt is made to demonstrate that these triple junctions embody strain fields and excess elastic energies which depend upon the misorientations of the grain boundaries in calculable ways. This represents a new approach to triple line studies. %%% The overall thrust of this project is to study how the terminations of grain boundaries affect their properties and behavior. This is important in polycrystalline thin films used in electronic applications and in the properties of nanocrystalline materials. ***

本项目结合理论和实验，研究自由表面和三重结对晶界结构、性能和行为的影响。传统的研究晶界性质的方法依赖于本质上无限的模型，相对较少关注与实际界面非无限范围相关的影响。在考虑表面松弛效应的情况下，计算了有限材料中由位错阵列构成的晶界弹性场。考虑了自由表面对位错的影响，以期理解如何从晶界消除位错，从而导致取向错误的变化。这些效应也在多晶薄膜中进行了原位透射电镜实验，并与计算结果进行了比较。该项目包括对多晶材料中三重结的性质和行为的研究。对于某些类型的材料，特别是薄膜，三重结可能属于有限的对称类，其中晶界能的各向异性对三重线的形态产生控制影响。试图以可计算的方式证明这些三重结包含应变场和多余的弹性能，这些弹性场和弹性能取决于晶界的取向偏差。这代表了三线研究的一种新方法。这个项目的主要目的是研究晶界的终止如何影响它们的性质和行为。这在电子应用中的多晶薄膜和纳米晶材料的特性中是很重要的。＊＊＊