Measurement of Annealing Phenomena in High Purity Metals with Near-field High Energy X-ray Diffraction Microscopy

• Main Author: Hefferan, Christopher M.
• Format: Others
• Published: Research Showcase @ CMU 2012
• Subjects: Physics
• Online Access: http://repository.cmu.edu/dissertations/135; http://repository.cmu.edu/cgi/viewcontent.cgi?article=1141&context=dissertations

The forward modeling method (FMM) for analysis of near-field High Energy X-ray Diffraction Microscopy (nfHEDM) has emerged as a powerful tool for materials characterization, with the ability to non-destructively measure microstructures deep within the bulk of materials. A synchrotron based technique, nfHEDM images X-ray diffraction from polycrystals with high resolution cameras. The diffraction signal is used to reconstruct the ensemble of grains in the form of 2D maps with high orientation and spatial resolution, and can be extended to volumetric measurements through sequential measurement. The hallmark of this technique is the ability to monitor the same ensemble of grains as they evolve in response to an external stimuli. This thesis will investigate the response of microstructure to annealing. The three thermally activated phenomena of recovery, recrystallization, and grain growth will be observed with two high purity metal wire samples. The first measurement, performed on aluminum, demonstrates the replacement of a deformed microstructure with well ordered grains in the recovery and recrystallization processes. A grain growth measurement performed on a fully recrystallized nickel sample demonstrates sensitivity to the evolution of a population of low energy grain boundaries, common to many fcc metals.