A Phase-Field Study of Spinodal Decomposition Impeded by Irradiation in U-Mo and U-Mo-Zr Alloys.

Abstract

The phase-field method, coupled with the micro-elastic model and irradiation-induced cascade mixing model, has been employed to investigate the spinodal decomposition in U-Mo and U-Mo-Zr alloys. The microstructure evolution of U-Mo or U-Mo-Zr alloys under different initial conditions, such as the alloy composition, aging temperature and irradiation intensity, were simulated to study the effect of cascade mixing on the miscibility gap, morphology and volume fraction of the decomposed phases. The simulation results demonstrate that irradiation-induced cascade mixing impedes the process of spinodal decomposition, and that irradiation shrinks the composition range of the miscibility gap in the alloys. Irradiation-induced cascade mixing slows down the anisotropic growth rate of the spinodal decomposition, yet this phenomenon can be weakened with increasing aging temperature. Adding an appropriate amount of Zr to a U-Mo alloy can effectively prevent the contraction of the miscibility gap caused by irradiation.