TY - JOUR
T1 - Early stage damage of ultrafine-grained tungsten materials exposed to low energy helium ion irradiation
AU - El-Atwani, O.
AU - Gonderman, S.
AU - Suslov, S.
AU - Efe, M.
AU - De Temmerman, G.
AU - Morgan, T.
AU - Bystrov, K.
AU - Hattar, K.
AU - Allain, J. P.
N1 - Funding Information:
The authors acknowledge Daniel Klenosky and Tian Qiu for the help in preparing the samples prior to irradiation. This research is supported by the U.S. Department of Energy ’s 2010 Early Career Award DE-SC0004032 . The FOM authors are supported by the Stichting voor Fundamenteel Onderzoek der Materie (FOM), which is financially supported by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO). The work is supported by the European Communities under the contract of Association between EURATOM and FOM and carried out within the framework of the European Fusion Program, and of the European Taskforce on Plasma-Wall Interactions. K. Hattar acknowledges the Division of Materials Science and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. The authors would like to thank Professor Anter El-Azab for the helpful discussions.
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/4/1
Y1 - 2015/4/1
N2 - Tungsten is considered as a plasma facing component in the divertor region of the International Thermonuclear Experiment Reactor (ITER). High flux, high fluence helium (He) exposure of tungsten surfaces induces severe morphology changes and nanostructure formation, which may eventually erode tungsten and risk the operation of the reactor. In this study, we investigate the response of ultrafine-grained tungsten under low flux (∼1020 ions m-2 s-1), low fluence, low energy (30-70 eV) He irradiation at different temperatures in order to study the early stage of nanostructure formation. Rod-shape nanostructures formed at low temperatures (600 °C) and a He fluence of 1 × 1023 m-2. High resolution, cross-section TEM images of irradiated grains demonstrated bubble formation not inside the nanostructures but deep inside the grains. At higher temperatures (900 °C) and the same fluence of 1 × 1023 m-2, large tungsten asperities (stone-shape and fiber-form structures), which are attributed to the burst and erosion of the surface grains. Moreover, low fluence (1020 m-2-1021 m-2) and high temperature (900 °C) irradiation demonstrated low density of non-coalesced bubbles inside the TEM samples. The results suggest that morphology changes can exist in He irradiated tungsten even with low bubble densities; thus, an additional factor such as surface stresses may dictate the observed nanostructure formation.
AB - Tungsten is considered as a plasma facing component in the divertor region of the International Thermonuclear Experiment Reactor (ITER). High flux, high fluence helium (He) exposure of tungsten surfaces induces severe morphology changes and nanostructure formation, which may eventually erode tungsten and risk the operation of the reactor. In this study, we investigate the response of ultrafine-grained tungsten under low flux (∼1020 ions m-2 s-1), low fluence, low energy (30-70 eV) He irradiation at different temperatures in order to study the early stage of nanostructure formation. Rod-shape nanostructures formed at low temperatures (600 °C) and a He fluence of 1 × 1023 m-2. High resolution, cross-section TEM images of irradiated grains demonstrated bubble formation not inside the nanostructures but deep inside the grains. At higher temperatures (900 °C) and the same fluence of 1 × 1023 m-2, large tungsten asperities (stone-shape and fiber-form structures), which are attributed to the burst and erosion of the surface grains. Moreover, low fluence (1020 m-2-1021 m-2) and high temperature (900 °C) irradiation demonstrated low density of non-coalesced bubbles inside the TEM samples. The results suggest that morphology changes can exist in He irradiated tungsten even with low bubble densities; thus, an additional factor such as surface stresses may dictate the observed nanostructure formation.
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U2 - 10.1016/j.fusengdes.2015.02.001
DO - 10.1016/j.fusengdes.2015.02.001
M3 - Article
AN - SCOPUS:84925630033
SN - 0920-3796
VL - 93
SP - 9
EP - 14
JO - Fusion Engineering and Design
JF - Fusion Engineering and Design
ER -