钚镓合金中氦气泡形成演化的相场模拟

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

摘要:

钚镓（Pu-Ga）合金是一种重要的核材料，氦泡形核生长严重影响其微观组织演变和力学性能变化。本工作建立了室温时效条件下Pu-Ga合金中氦泡形成演化的相场模型，分析了不同时效时间和温度下的氦气泡的形貌演变规律，根据相场模拟结果统计了氦气泡的平均直径和数密度的变化曲线。研究发现，室温时效下气泡的尺寸和位置几乎不会发生变化，而气泡数密度呈直线增长，模拟结果与公开发表的实验结果符合较好。分析发现，时效温度主要通过影响点缺陷的迁移率，从而影响气泡生长速率，而室温时扩散系数非常低是导致室温下Pu-Ga合金中氦泡尺寸和数密度特殊演化趋势的主要原因。本工作为准确预测Pu-Ga合金中氦泡生长行为提供了介观尺度理论模型。

Abstract:

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.