Issue 33, 2023, Issue in Progress

Molecular dynamics exploration of helium bubble nucleation and growth mechanisms in Fe70Ni11Cr19 austenitic stainless steel

Abstract

The growth of helium bubbles impacts structural integrity of materials in nuclear applications. Understanding helium bubble nucleation and growth mechanisms is critical for improved material applications and aging predictions. Systematic molecular dynamics simulations have been performed to study helium bubble nucleation and growth mechanisms in Fe70Ni11Cr19 stainless steels. First, helium cluster diffusivities are calculated at a variety of helium cluster sizes and temperatures for systems with and without dislocations. Second, the process of diffusion of helium atoms to join existing helium bubbles is not deterministic and is hence studied using ensemble simulations for systems with and without vacancies, interstitials, and dislocations. We find that bubble nucleation depends on diffusion of not only single helium atoms, but also small helium clusters. Defects such as vacancies and dislocations can significantly impact the diffusion kinetics due to the trapping effects. Vacancies always increase the time for helium atoms to join existing bubbles due to the short-range trapping effect. This promotes bubble nucleation as opposed to bubble growth. Interestingly, dislocations can create a long-range trapping effect that reduces the time for helium atoms to join existing bubbles. This can promote bubble growth within a certain region near dislocations.

Graphical abstract: Molecular dynamics exploration of helium bubble nucleation and growth mechanisms in Fe70Ni11Cr19 austenitic stainless steel

Article information

Article type
Paper
Submitted
13 Jun 2023
Accepted
27 Jul 2023
First published
01 Aug 2023
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2023,13, 23236-23243

Molecular dynamics exploration of helium bubble nucleation and growth mechanisms in Fe70Ni11Cr19 austenitic stainless steel

X. W. Zhou, RSC Adv., 2023, 13, 23236 DOI: 10.1039/D3RA03969B

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