Atomistic Study of the Structure, Thermodynamics, and Morphological Evolution of Uranium-Zirconium Alloys

Abstract

An atomistic study of U-Zr alloys was conducted, a promising nuclear reactor metallic fuel. A semi-empirical modified embedded atom method (MEAM) potential was developed for application to the high temperature body-centered-cubic uranium-zirconium alloy (γ-U-Zr) phase and checked against numerous first principles and experimental properties. The potential was then used to examine some of the high temperature thermodynamics and structure, and was able to obtain new values for the isothermal compressibility, adiabatic index, and the Grüneisen parameters for the U-Zr phase at temperature. In many metallic alloys, complex microstructures form as a consequence of local atomic ordering that depends on the processing path. This research uses an atomistic approach to study microstructural morphology and evolution by investigating how temperature and alloy concentration affect ordering behaviors that lead to observed microstructures. Finally, a sensitivity analysis of the MEAM potential was performed in order to examine and understand the uncertainty in the parameters and formalism of the interatomic potential. The sensitivity analysis was conducted using one-at-a-time (OAT) sampling of the parameters and how they affected the ground state, thermal, and alloy structural and thermodynamic properties.