Byggmästar J, Granberg F, Sand A E, Pirttikoski A, Alexander R, Marinica M-C, Nordlund K
Department of Physics, University of Helsinki, Helsinki, PO Box 43, FIN-00014, Finland.
J Phys Condens Matter. 2019 Jun 19;31(24):245402. doi: 10.1088/1361-648X/ab0682. Epub 2019 Feb 12.
Overlap of collision cascades with previously formed defect clusters become increasingly likely at radiation doses typical for materials in nuclear reactors. Using molecular dynamics, we systematically investigate the effects of different pre-existing self-interstitial clusters on the damage produced by an overlapping cascade in bcc iron and tungsten. We find that the number of new Frenkel pairs created in direct overlap with an interstitial cluster is reduced to essentially zero, when the size of the defect cluster is comparable to that of the disordered cascade volume. We develop an analytical model for this reduced defect production as a function of the spatial overlap between a cascade and a defect cluster of a given size. Furthermore, we discuss cascade-induced changes in the morphology of self-interstitial clusters, including transformations between [Formula: see text] and [Formula: see text] dislocation loops in iron and tungsten, and between C15 clusters and dislocation loops in iron. Our results provide crucial new cascade-overlap effects to be taken into account in multi-scale modelling of radiation damage in bcc metals.
在核反应堆材料典型的辐射剂量下，碰撞级联与先前形成的缺陷团簇重叠的可能性越来越大。我们使用分子动力学方法，系统地研究了不同预先存在的自间隙团簇对体心立方铁和钨中重叠级联产生的损伤的影响。我们发现，当缺陷团簇的尺寸与无序级联体积的尺寸相当时，与间隙团簇直接重叠产生的新弗伦克尔对数量基本减少到零。我们针对这种缺陷产生减少的情况，开发了一个分析模型，该模型是级联与给定尺寸缺陷团簇之间空间重叠的函数。此外，我们讨论了级联引起的自间隙团簇形态变化，包括铁和钨中〈110〉和〈112〉位错环之间以及铁中C15团簇和位错环之间的转变。我们的结果为体心立方金属辐射损伤的多尺度建模提供了关键的新级联重叠效应，需加以考虑。
