Helium bubbles diffusion in aluminum: Influence of gas pressure

A Antropov and V Stegailov, JOURNAL OF NUCLEAR MATERIALS, 573, 154123 (2023).

DOI: 10.1016/j.jnucmat.2022.154123

The influence of helium pressure on the mechanisms of diffusion of the He-filled nanobubbles in fcc Al is investigated by the classical molecular dynamics. It is shown that at pressures < 20 kbar gas sup- presses self-diffusion, while the concentration of adatoms, rather than their mobility, plays a key role. However, as the pressure increases to values at which the bubble emits self-interstitial atoms, the sur-face self-diffusion and bubble diffusion coefficients begin to increase. It is shown that the bubble diffusion coefficient is proportional to the concentration of self-interstitial atoms in the surface layer. At higher gas pressures, self-interstitial atoms form dislocation loops around the bubble and bubble diffusion coeffi-cient drops significantly. The effect of surface self-diffusion suppression by gas pressure cannot explain the experimental data, while they can be explained by dislocation loops formation around bubbles. Two interatomic interactions models for Al-He system are considered. It is shown that the main findings of this work do not depend on the choice of the model.(c) 2022 Elsevier B.V. All rights reserved.

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