9303518 Reynolds This research examines the fundamental mechanisms governing precipitate morphology in metal alloys. The measurement of growth ledge nucleation kinetics as a function of interphase boundary orientation provides necessary information to unify two current theories for the development of precipitate morphology: the general theory for precipitate morphology, which relates precipitate shape to boundary mobilities, and the invariant line theory, which predicts precipitate orientation relationships, growth directions, and habit planes from the crystallography of the phases involved. Experimental observation of the misfit dislocation structures at precipitate/matrix boundaries during growth in a nickel-chromium alloy provides information on mechanisms by which partially coherent boundaries migrate in solids. %%% The long term benefit of the research is understanding of the physical processes responsible for microstructural evolution, which guides improvement in commercial metal alloys. ***
