High Flux Helium Irradiation of Dispersion-Strengthened Tungsten Alloys and Effects of Heavy Metal Impurity Layer Deposition

JOURNAL OF NUCLEAR MATERIALS

卷:544

Article

Lang, E.¹  Kapat, A.¹  Morgan, T. W.²  Allain, J. P.³ 

[1] Univ Illinois, Dept Nucl Plasma & Radiol Engn, Urbana, IL USA

[2] DIFFER Dutch Inst Fundamental Energy Res, De Zaale 20, NL-5612 AJ Eindhoven, Netherlands

[3] Penn State Univ, Ken & Mary Alice Lindquist Dept Nucl Engn, State Coll, PA USA

关键词: Dispersion-strengthened tungsten;    Tungsten;    Helium irradiation;    Surface impurity layer;   

DOI  :  10.1016/j.jnucmat.2020.152672

来源: Elsevier

【 摘 要 】

Tungsten has been chosen as the plasma-facing material (PFM) for the divertor region in ITER and also a candidate PFM for future plasma-burning nuclear fusion reactors. During fusion device operation, PFMs will be exposed to low-energy He irradiation at high temperatures, resulting in sub-surface bubbles and surface morphology changes such as pores and fuzz. Carbide dispersion-strengthened W materials may enhance the ductility of W, but their behavior under high flux He irradiation remains unclear. In this work, the response of dispersion-strengthened tungsten materials to high flux, low energy He irradiation at high temperature is examined. Tungsten alloyed with 1, 5, or 10 wt. % tantalum carbide or titanium carbide exposed to these conditions result in surface pores, coral-like feature growth and sub-surface helium bubbles. Reactor-relevant helium irradiation (5x10(26)m(-2) fluence) combined with high powered laser pulses to simulate off-normal reactor events does not significantly alter the surface morphology, as the surface nanostructures appear stable and cracks are only observed on a localized region of one sample. However, specimens show the development of an impurity layer on the surface, likely impurity deposition from the sample holder during irradiation, resulting in a mixed material layer on the surface. Helium bubbles exist in this impurity layer, and obscure conclusions about helium interactions with the carbide dispersoids. Nonetheless, it is clear that the dispersoid microstructure limits He bubble formation and subsequent surface nanostructuring, attributed to the dispersoid composition. (C) 2020 Elsevier B.V. All rights reserved.

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