Deuterium retention in chemically vapor deposited tungsten carbide coatings and hot-rolled tungsten exposed to low-energy deuterium plasmaстатья
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Дата последнего поиска статьи во внешних источниках: 1 июня 2022 г.
Аннотация:Chemically vapor deposited (CVD) tungsten carbides coatings W45C55 and W60C40 and hot-rolled tungsten were exposed to low-energy (about 200 eV/D) deuterium plasma with an ion flux of about 1.1×1021 D/m2s to a fluence of about 2×1024 D/m2 at sample temperatures ranging from 323 to 813 K. The concentration of deuterium in these samples was examined by the D(3He,p)4He nuclear reaction. Based on the measured deuterium depth profiles and assuming that these profiles are determined by diffusing D atoms, the diffusion coefficients of deuterium in the CVD tungsten carbide coatings were determined. Using these diffusion coefficients, an estimate of the Arrhenius relation for the diffusion coefficients of deuterium in CVD tungsten carbide coatings was obtained: D = 2.5×10-3 exp(-1.12 eV/kT) m2s. The concentration of trapped deuterium in the bulk of CVD tungsten carbide coatings is practically independent of the stoichiometry of the coatings. It decreases from about 5×10-2 to about 7×10-4 D/(W+C) with an increase in the deuterium plasma exposure temperature from 373 to 813 K. The concentration of trapped deuterium in hot-rolled tungsten, expressed in units of the D/W atomic ratio, is more than an order of magnitude lower than the concentration of deuterium in tungsten carbides, and also decreases with increasing plasma exposure temperature.