Thermodynamic and diffusion databases for uranium-based alloys and their applications in materials design

Abstract

Thermodynamic and diffusion databases are of fundamental importance for material design. In this work, the thermodynamic and diffusion databases for multicomponent U alloys are developed using the CALPHAD (CALculation of PHAse Diagram) method. Thermodynamic models are employed to describe all phases in the UNbZrTiMoC system in which 7 ternary systems (UNbZr, UZrTi, UMoZr, MoNbZr, MoTiZr, CNbZr, and CNbTi) are thermodynamically assessed. Thermodynamic descriptions of all sub-systems from both literature and present assessments are integrated into the database with a proper adjustment. The diffusion database is developed for bcc and liquid phases in the UNbZrTiMoC system. Applications of thermodynamic and diffusion databases are performed using two cases including (a) the stability of γU in the multicomponent system, and (b) discontinuous precipitation simulation in U-14 at.% Nb alloys. It is expected that further progress in CALPHAD-type nuclear materials databases will be an effective contribution to advanced metal fuels design.