Date of Award
Doctor of Philosophy (PhD)
Robert M. Suter
Near-field High Energy X-ray Diffraction Microscopy (HEDM) is a synchrotron based imaging technique capable of resolving crystallographic orientation in a bulk, polycrystalline material non-destructively. Recent advances in data acquisition and analysis methods have led to micron-scale spatial resolution and ≤ 0.1º angular resolution of the measured volumetric orientation maps across millimeter sized samples. This is a significant improvement over the previous generation of three-dimensional X-ray techniques, which provides us with the access of statistically significant microstructure volumes. Combined with the use of state-of-the-art surface mesh generation algorithms, this markedly improved resolution results in the capability to directly measure geometrical evolution, such as grain boundary motion, and material deformation in the form of lattice rotations.
In this thesis, the algorithms and analysis methods recently developed for HEDM are discussed. This includes the descriptions of the robust geometrical extraction methods used for microstructure feature characterization. A set of validation tests for the Forward Modeling Method and the newly developed orientation reconstruction algorithm, the Stratified Monte Carlo Pruning method, is also detailed. By using HEDM to measure the annealing of high purity nickel, grain boundary motion for different boundary types are measured and presented. Moreover, the use of HEDM enabled us to observe the first ever spatially resolved lattice rotation in a high purity copper wire under uni-axial tension, thus demonstrating HEDM’s applicability to defected materials.
Li, Shiu Fai Frankie, "Imaging of Orientation and Geometry in Microstructures: Development and Applications of High Energy X-ray Diffraction Microscopy" (2011). Dissertations. Paper 59.