Grain growth in U–7Mo alloy: A combined first-principles and phase field study

Grain size is an important factor in controlling the swelling behavior in irradiated U–Mo dispersion fuels. Increasing the grain size in U–Mo fuel particles by heat treatment is believed to delay the fuel swelling at high fission density. In this work, a multiscale simulation approach combining first-principles calculation and phase field modeling is used to investigate the grain growth behavior in U–7Mo alloy. The density functional theory based first-principles calculations were used to predict the material properties of U–7Mo alloy. The obtained grain boundary energies were then adopted as an input parameter for mesoscale phase field simulations. The effects of annealing temperature, annealing time and initial grain structures of fuel particles on the grain growth in U–7Mo alloy were examined. The predicted grain growth rate compares well with the empirical correlation derived from experiments.