Direct observation of the spatial distribution of primary cascade damage in tungsten. (1st February 2018)

• Record Type: Journal Article
• Authors: Mason, D.R.; Sand, A.E.; Yi, X.; Dudarev, S.L.
• Is Part Of: Acta materialia. Volume 144(2018)
• Page Start: 905
• Page End: 917
• Publication Date: 2018-02-01
• Subjects: Irradiation damage -- Electron microscopy -- Defect clusters -- Spatial correlation; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2017.10.031
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: 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. Graphical abstract: Image 1