Atomic Structure, Growth Mechanisms and Kinetics of Precipitate Interfaces in Metal Alloys

本研究的目的是考察金属合金中析出相界面的原子结构、生长机制和动力学，并与已发展的描述界面结构和界面生长动力学的理论模型进行比较。用高分辨电子显微镜(HRTEM)测量了平行和垂直于惯性面的薄箔样品中沉淀板的三维原子结构。通过原位热阶段HRTEM实验确定了界面生长的原子机制和动力学，并与在高压透射电子显微镜下对较厚的样品进行的热阶段实验进行了比较，后者最大限度地减少了表面效应对相变的影响。得到的动力学测量结果与沉淀生长的动力学模型进行了比较。选择了三种不同类型的合金系统进行研究。%本程序中生成的知识是理解固体相界特性的基础。这一理解可以应用于定制技术上有用的材料的性能。

The purpose of this research is to examine the atomic structure, growth mechanisms, and kinetics of precipitate interfaces in metal alloys for comparison with theoretical models that have been developed to describe interfacial structure and growth kinetics of interphase boundaries. High resolution transmission electron microscopy (HRTEM) is used to determine the three-dimensional atomic structure of precipitate plates in thin foil specimens both parallel and perpendicular to the habit plane. Atomic mechanisms and kinetics of interface growth are determined by in situ hot stage HRTEM experiments and compared to hot stage experiments on thicker specimens in a high voltage TEM where the role of surface effects on the transformation are minimized. Resulting kinetic measurements are compared with kinetic models of precipitate growth. Three different types of alloy systems are selected for the studies. %%% The knowledge generated in this program is fundamental to the understanding of the properties of interphase boundaries in solids. This understanding can be applied to tailoring the properties of technologically useful materials.