Orientation imaging microscopy: Emerging and future applications

Orientation imaging microscopy (OIM), which images the microstructure using the electron backscattered diffraction probe, has proven to be a powerful tool for the study of polycrystalline materials. OIM's chief strength lies in its ability to couple the morphological aspects of microstructure, with lattice orientation. With spatial and angular resolution of at least 100 nm and 1 degrees, OIM is ideally suited to investigations at the mesoscale. In this paper three examples are described which illustrate emerging and future applications of OIM to important problems in materials science at the mesoscale. The first example is the use of higher-order point statistics to obtain improved bounds on structure-insensitive properties. It is emphasized that the approach may be used, not only to enhance material properties, but also to control their variability. The second example is an emerging analysis to map the relationships between the character (type) of grain boundaries and their intrinsic properties. The main idea is illustrated for mappings linking character and excess free energy. The third example focuses on the ability of OIM to measure lattice curvature, and to thereby obtain information about the geometrically necessary dislocation content of the microstructure. This example is illustrated by analysis to extract the dislocation density tenser.