Changes in dislocation punching behavior due to hydrogen-seeded helium bubble growth in tungsten

Journal Article · 09 December 2024 · Journal of Nuclear Materials

DOI: https://doi.org/10.1016/j.jnucmat.2024.155555 · OSTI ID:2481558

Hatton, Peter John  ^[1]; Perez, Danny  ^[1]; Uberuaga, Blas Pedro  ^[1]

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1. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

The accumulation of gas atoms in tungsten is a topic of long-standing interest to the plasma-facing materials community due the metal's use as a divertor material in some tokamak fusion reactors. The nucleation and growth of He/H gas bubbles (along with their isotopes) can result from impinging fluxes of these gases which give rise to damage at the W divertor surface. The inclusion of He or H in W has been studied extensively by the community, finding that He bubbles modify the surface through periodic dislocation punching and bursting mechanisms while H bubbles impact the metal through plastic-strain induced material failure. However, the mechanisms which are present during the combined flux of both He and H is not well-studied atomistically. Motivated by this, an atomistic modeling study is conducted using molecular dynamics to assess the behavior of mixed concentration He:H bubbles in W. Here we find that the introduction of H into a growing He bubble results in a dramatic change in the nature and presence of dislocation loops which are typically generated via dislocation punching in over-pressurized He bubbles. Most notably, at high H concentrations, there is a switchover in energetic favorability from glissile 1/2<111> dislocations to sessile <100> dislocations. This thermodynamic crossover could imply a significant reduction in W surface morphology changes than with pure He bubbles and, additionally, we show this to have implications on the trapping of H in the bubbles and their associated dislocations.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR). Scientific Discovery through Advanced Computing (SciDAC); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• Grant/Contract Number: AC05-00OR22725; 89233218CNA000001
• OSTI ID: 2481558
• Report Number(s): LA-UR--24-27110
• Journal Information: Journal of Nuclear Materials, Journal Name: Journal of Nuclear Materials Vol. 605; ISSN 0022-3115
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English