Observation of interstitial loops in He+ irradiated W by conductive atomic force microscopy

• Published in: Acta materialia Vol. 92; pp. 178 - 188
• Main Authors: Yang, Qi, Fan, Hongyu, Ni, Weiyuan, Liu, Lu, Berthold, Tobias, Benstetter, Günther, Liu, Dongping, Wang, Younian
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.06.2015
• Subjects: Atomic force microscopy; Conductive atomic force microscopy; Energy distribution; Fluence; Interstitials; Irradiation; Nanostructure; Surface temperature; Tungsten; Conductive atomic force microscopy; Irradiation; Tungsten
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2015.04.004

Polycrystalline tungsten (W) has been irradiated with a low-energy (30–830eV) He+ beam at the W surface temperature of 523–1073K up to a fluence of 1.0×1025/m2. Measurements by non-destructive conductive atomic force microscopy show the existence of nanometer-sized interstitial loops in He+-implanted layer. The size and distribution of interstitial loops are significantly affected by He+ energy and fluence, and W surface temperature. The distribution of interstitial loops becomes orientated in one certain direction after being irradiated at a relatively high fluence or W surface temperature. The cascading slipping of W atoms along one certain dense-packed face has been proposed to explain the ordered arrangement of interstitial loops at elevated temperature. Analysis indicates that the continuous growth of unstable nanometer-sized interstitial loops can result in the surface exfoliation of W materials.