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

本研究的目的是研究金属合金中析出相界面的原子结构、生长机制和动力学，并与已经开发的描述界面结构和界面生长动力学的理论模型进行比较。采用高分辨率透射电子显微镜（HRTEM）对平行于习惯面和垂直于习惯面的薄片试样中析出相板的三维原子结构进行了测定。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，并与高压TEM中较厚样品的热阶段实验进行了比较，其中表面效应对转变的作用最小。所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体系进行研究。在这个程序中产生的知识是理解固体相间边界性质的基础。这种理解可以应用于裁剪技术上有用的材料的特性。

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.