Hu Yi-Yu, Xie Yao-Ping, Wu Lu, Qin Jian-Tao, Pan Rong-Jian, Yao Mei-Yi
School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China.
The First Sub-Institute, Science and Technology on Reactor Fuel and Materials Laboratory, Nuclear Power Institute of China, Chengdu 610005, China.
Materials (Basel). 2022 Feb 8;15(3):1267. doi: 10.3390/ma15031267.
Ferritic/martensitic (F/M) steels whose matrix is Fe-Cr are important candidate materials for fuel cladding of fast reactors, and they have excellent irradiation-swelling resistance. However, the mechanism of irradiation-swelling of F/M steels is still unclear. We use a first-principles method to reveal the influence of irradiation defects, i.e., Frenkel pair including atomic vacancy and self-interstitial atom, on the change of lattice volume of Fe-13Cr lattice. It is found that vacancy causes lattice contraction, while a self-interstitial atom causes lattice expansion. The overall effect of a Frenkel pair on the change of lattice volume is lattice expansion, leading to swelling of the alloy. Furthermore, the diffusion properties of point defects in Fe-13Cr are investigated. Based on the diffusion barriers of the vacancies and interstitial atoms, we find that the defects in Fe-13Cr drain out to surfaces/grain boundaries more efficiently than those in pure α-Fe do. Therefore, the faster diffusion of defects in Fe-13Cr is one of important factors for good swelling resistance of Fe-13Cr compared to pure α-Fe.
铁素体/马氏体（F/M）钢以铁铬为基体，是快中子反应堆燃料包壳的重要候选材料，具有优异的抗辐照肿胀性能。然而，F/M钢的辐照肿胀机制仍不明确。我们采用第一性原理方法来揭示辐照缺陷，即包括原子空位和自间隙原子的弗伦克尔对，对Fe-13Cr晶格体积变化的影响。研究发现，空位导致晶格收缩，而自间隙原子导致晶格膨胀。弗伦克尔对晶格体积变化的总体影响是晶格膨胀，导致合金肿胀。此外，还研究了Fe-13Cr中点缺陷的扩散特性。基于空位和间隙原子的扩散势垒，我们发现Fe-13Cr中的缺陷比纯α-Fe中的缺陷更有效地向表面/晶界排出。因此，与纯α-Fe相比，Fe-13Cr中缺陷的更快扩散是其具有良好抗肿胀性能的重要因素之一。
