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

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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.