This project combines theoretical and experimental studies of grain boundary structure and properties, particularly as related to polycrystalline aggregates. Attention is given to types of line defects not studied previously in grain boundaries and to the effects of finite grain boundary length. Computer-based experiments examine the effects of finite boundary size upon boundary structure with relevance to nanocrystalline materials. The nature and behavior of triple lines and associated defects (disclinations) are studied using computational techniques for the analysis of their geometries and experiments on copper tricrystals. Experiments are aimed at determining energy vs. misorientation relationships for grain boundaries in non-cubic materials. Transmission electron microscopy of tricrystals is employed to determine defect structure and grain boundary energies in selected metal specimens. %%% This project has as an overall goal to develop detailed understanding of the mechanisms by which grain boundary structure determines grain boundary properties. This is pertinent to all polycrystalline materials, but is particularly relevant to the new class of nanostructured materials now seeing increased research attention.
