Phase-Field Simulation of Helium Bubble Formation in Pu-Ga Alloy

Pu-Ga alloys are vital nuclear materials. However, the nucleation and growth of helium bubbles significantly affect their microstructural evolution and mechanical properties. In this work, a phase-field model was developed to simulate the formation and evolution of helium bubbles in Pu-Ga alloys during room-temperature aging. The model analyzed the morphological evolution of helium bubbles under different aging time and temperatures. According to phase-field simulation results, the variation curves of average diameter and number density of bubbles were obtained. The results show that at room temperature, bubble size and spatial distribution remain nearly unchanged, while the number density increases linearly. These simulation results align well with published experimental data. Further analysis indicates that aging temperature primarily affects growth kinetics of bubbles by influencing point defect mobility rate. In contrast, the exceptionally low diffusion coefficient at room temperature is the key factor leading to the unique evolution trends observed in bubble size and number density. This study provides a mesoscale theoretical model for accurately predicting the growth behavior of helium bubble in Pu-Ga alloys.