Title: Towards a better understanding of phase transformations in uranium alloys
Abstract: This proposed dissertation research work will further the understanding of high temperature aging on uranium-niobium (U-Nb) and uranium-molybdenum (U-Mo) alloys, primarily through the use of in-situ and exsitu x-ray/neutron scattering experiments. Both of these materials have drawn interest due to their unique properties, which are significant improvements when compared to pure metallic uranium. U-10wt%Mo has been identified and selected as the candidate LEU nuclear reactor fuel replacement for currently used HEU fuels in research reactors in the United States. U-6wt%Nb has an ideal combination of corrosion resistance and ductility when in the monoclinic, martensite phase, as compared to pure, orthorhombic α-U. As with many metals, additional thermo-mechanical processing is required to obtain a desired shape, thus a complete understanding of the phase transformation kinetics in both systems is essential. While these material systems have rather specialized applications, the techniques developed in this work can readily be applied for the study of phase transformations in other systems.
The choice of x-ray/neutron scattering experiments as the primary vehicle for data collection rests on the ability to simultaneously obtain information about the phase transformations in-situ (at high temperatures) and at a wide range of length scales, depending on the experiment configuration. This ultimately provides information on a wide variety of metrics, such as phase weight fractions, phase crystallography, and microstructural aspects such as crystallographic texture, precipitate morphology, and precipitate size distributions. With respect to crystallographic texture measurements specifically, the use of different neutron diffractometers located at Oak Ridge National Laboratory are proposed, as is participation in a round robin study conducted at neutron scattering facilities worldwide.
Ji Ma, MSE, Chair
Sean Agnew, Advisor
Prasanna Balachandran, MSE
Houston Wood, MAE
Donald Brown, Los Alamos National Laboratory
Robert Hackenberg, Los Alamos National Laboratory
For ZOOM Meeting details, contact Peggy Gibson