IRGs

The mission of the MIMP is to understand the mechanistic origins of the grain boundary character distribution, a five-dimensional materials specific quantity, and its influence on the macroscopic properties and performance of polycrystalline materials. Our integrated program of theory, experiment, and simulation leverages the skills of scientists and engineers from multiple disciplines. The development of experimental tools with expanded spatial and temporal resolutions allows new observations to be made of the three-dimensional structure of the grain boundary network. It is therefore be possible to make rigorous statistical comparisons to the results of large-scale simulations of microstructural evolution that accurately depict thermodynamic rules for interface motion and model the full crystallographic complexity of the grain boundary network. Through these studies, we will define the statistical quantities required for a theory of grain boundary network evolution. We will also identify metrics that can be related to grain boundary sensitive mechanical and electrical properties. Our experimental studies will concentrate on the internal structures and grain boundary properties of Al aerospace alloys, Ni-based alloys, thin film Cu for interconnections, dielectric ceramics, ceramic cutting tools, and grain boundary engineered brass, Pb, and Ni. A three-dimensional orientation mapping system based on a dual beam focused ion beam scanning electron microscope will be used to extract true three-dimensional microstructural data. In addition, a transmission electron microscope system will be used to map orientations in materials with nanometer scale resolution, and a three-dimensional x-ray diffraction microscope will be used to study microstructure evolution in situ.