Direct observation of the spatial distribution of primary cascade damage in tungsten

作者：Mason, D. R.^*; Sand, A. E.; Yi, X.; Dudarev, S. L.

来源：Acta Materialia, 2018, 144: 905-917.

DOI：10.1016/j.actamat.2017.10.031

• Irradiation damage
• Electron microscopy
• Defect clusters
• Spatial correlation

Recently we have presented direct experimental evidence for large defect clusters being formed in primary damage cascades in self-ion irradiated tungsten [Yi et al., EPL 110:36001 (2015)]. This large size is significant, as it implies that strong elastic interaction between the defects will affect their subsequent evolution, especially if defects are formed close together. Here we present a direct experimental observation of the separation between visible defects in self-ion irradiated tungsten, in the form of a 2d pairwise radial distribution function extracted from transmission electron micrographs (TEM). We also present a detailed analysis of the observed radial distribution function, and infer the probable size and shape of individual cascades. We propose and validate a simple exponential form for the spatial distribution of defects within a single cascade. The cascade statistics necessary have been acquired by developing an automated procedure for analysing black-dot damage in TEM micrographs. We confirm that the same model also produces a high-quality fit to the separation between larger defects observed in MD simulations. For the first time we present experimental evidence for the sub-nanometre-scale spatial distribution of defect clusters within individual cascades.

• 出版日期2018-2-1
• 单位北京科技大学