Journal
NUCLEAR FUSION
Volume 59, Issue 2, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/1741-4326/aaf297
Keywords
tungsten-transition metal alloys; alloying solutes; mixed self-interstitial atoms; helium clustering; nuclear fusion; plasma-facing material
Categories
Funding
- National Magnetic Confinement Fusion Program [2015GB112001]
- National Key Research and Development Program of China [2017YFA0402800]
- National Natural Science Foundation of China [11735015, 51771184, 11575231, 11575229, 51671185]
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In a fusion reactor environment, the irradiation of neutrons and helium (He) plasma produces a great number of self-interstitial atoms and vacancies in tungsten (W), which inevitably interact with alloying solutes to form mixed self-interstitial atoms and substitutional solutes. The interactions of solutes with He atoms affect the behaviors of both, and ultimately cause the formation of solute precipitates and He bubbles; however, the micro-mechanisms of this are still mysterious. In this work, we perform systematic ab initio calculations to study the mutual influence of solutes and I u atoms on their behaviors. It is found that most of the considered solutes bind tightly with the most stable < 1 1 1 > dumbbells forming mixed < 1 1 0 > or < 1 1 1 > dumbbells. Solute-mixed dumbbells can act as trapping centers for He atoms. Mixed dumbbells bind very tightly with interstitial He atoms and all the binding energies are larger than 1.0 eV. Compared with the energy for the formation of a W Frenkel pair with the presence of He, the energies needed for the formation of most solute-mixed Frenkel pairs are decreased while titanium, zirconium, niobitum, hafnium, and tantalum-mixed Frenkel pairs are exceptions. Similarly, substitutional solutes can also trap interstitial and substitutional He atoms, and 3d solutes bind stronger with interstitial He followed by 4d and 5d solutes while it is the opposite for interactions of substitutional solutes with substitutional He atoms. The underlying reasons controlling the interactions of mixed dumbbells and substitutional solutes with interstitial and substitutional He atoms are analyzed.
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