Effect of Pre-Existing Helium Bubbles in Tungsten under High Energy Displacement Cascades

Abstract:

Molecular dynamics (MD) simulation was used to explore how models of W-He respond to irradiation induced damage. Displacement cascades up to 10 keV recoil energy were simulated for W-Σ17 and W-Σ17-He models. The pre-existing He bubbles within and around the grain boundary region have a major effect on the number and distribution of surviving Frenkel pairs. Frenkel pairs increased as the energy of the primary knock-on atom (PKA) increased across all models. Models containing pre-existing He bubbles showed a significant reduction in the number of surviving vacancies/SIAs compared to those without He bubbles. A large portion of point defects accumulate at the grain boundary which acts as a sink for defects during the recrystallization phase. The presence of He bubbles within or near the grain boundary region facilitates the defects generation, absorbs residual point defects, and form clusters. When He bubbles are located around the grain boundary, the number of surviving vacancies/SIAs decreased by 23% to 60% compared to models without He bubbles. However, for models with He bubbles located within the grain boundary structure, a much more extensive reduction occurred compared to models without He bubbles, which is between the range of 76% to 92%.

• Periodical: Key Engineering Materials (Volume 1032)
• Pages: 117-122
• DOI: https://doi.org/10.4028/p-i9stVJ
• Online since: November 2025
• Authors: Mohammad Abu-Shams*
• Keywords: Displacement Cascade, Frenkel Pairs, Helium, Molecular Dynamics, Tungsten

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