原子尺度下 FeCrAl 合金辐照损伤效应

Research on the Effects of Irradiation Damage of FeCrAl Alloys at the Atomic Scale

摘要

FeCrAl 合金作为重要的核反应堆燃料包壳候选材料，需深入掌握其在辐照条件下的损伤特征。利用分子动力学方法模拟了不同损伤剂量下该合金的级联碰撞过程，分析晶界与非晶结构演化特征，比较辐照前后的点缺陷、位错缺陷空间分布，揭示辐照损伤缺陷的产生及演化机制。结果表明：辐照过程产生大量点缺陷及缺陷团簇，且辐照损伤剂量越高，点缺陷团簇数量越多，缺陷成团率也越高；辐照引入的点缺陷聚集于晶界的两侧，使晶界与非晶结构原子增多，低剂量条件下晶界厚度加宽但未发生明显非晶化，而高剂量条件下晶体内以晶界为核心出现非晶相，且损伤剂量越高，非晶化程度越高；辐照还会导致晶体位错空间分布和总体密度变化，低剂量辐照后位错密度略高于辐照前，但高剂量下位错密度明显降低。

Abstract

As a promising candidate material for nuclear fuel cladding, it is important to understand the damage characteristics of FeCrAl alloy under irradiation conditions. The cascade collision process of the alloy at different doses of irradiation damage were simulated using molecular dynamics (MD) method. The evolution characteristics of grain boundary (GB) atoms and amorphous phases were analyzed, and the spatial distribution of point defects and dislocations before and after irradiation were compared to reveal the mechanisms of the generation and evolution of irradiation induced defects. The results show that a large number of point defects and defect clusters were introduced during irradiation, and the higher the irradiation damage dose, the larger the number of clusters and the higher the defect cluster fraction; The point defects introduced by the irradiation preferred to aggregate at GBs, which lead to an increase in the fractions of GB and amorphous atoms. The thickness of GB increased at low doses without significant amorphization, while at high doses amorphous phases were formed with GB as the core, and the higher the dose, the higher the degree of amorphization. The irradiation also lead to the changes in the spatial distribution and overall density of dislocations, which was slightly higher after irradiation at low doses than in the absence of irradiation, but would significantly decrease with the increase of dose.

关键词

FeCrAl合金 / 辐照损伤 / 微观机制 / 分子动力学

Key words

FeCrAl alloy / irradiation damage / microscopic mechanism / molecular dynamic

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基金资助

内蒙古自治区自然科学基金项目(2025QN05085)