Understanding the influence of hydrogen on BCC iron grain boundaries using the kinetic activation relaxation technique (k-ART)
Hydrogen embrittlement (HE) poses a significant challenge to the mechanical integrity of iron and its alloys. This study explores the influence of hydrogen atoms on two distinct grain boundaries (GBs), $\Sigma37$ and $\Sigma3$ , in body-centered-cubic (BCC) iron. Using the kinetic activation relaxat...
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IOP Publishing
2025-01-01
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| Online Access: | https://doi.org/10.1088/2515-7639/ada994 |
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| author | Aynour Khosravi Jun Song Normand Mousseau |
| author_facet | Aynour Khosravi Jun Song Normand Mousseau |
| author_sort | Aynour Khosravi |
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| description | Hydrogen embrittlement (HE) poses a significant challenge to the mechanical integrity of iron and its alloys. This study explores the influence of hydrogen atoms on two distinct grain boundaries (GBs), $\Sigma37$ and $\Sigma3$ , in body-centered-cubic (BCC) iron. Using the kinetic activation relaxation technique , an off-lattice kinetic Monte Carlo approach with an EAM-based potential, extensive catalogs of activated events for atoms in both H-free and H-saturated GBs were generated. Studying the diffusion of H, we find that, for these systems, while GB is energetically favorable for H, this element diffuses more slowly at the GBs than in the bulk. The results further indicate that the $\Sigma 3$ GB exhibits higher stability in its pure form compared to the $\Sigma 37$ GB, with notable differences in energy barriers and diffusion behaviors. Moreover, with detailed information about the evolution landscape around the GB, we find that the saturation of a GB with hydrogen both stabilizes the GB by shifting barriers associated with Fe diffusion to higher energies and reducing the number of diffusion events. For the $\Sigma 37$ GB, the presence of hydrogen causes elastic deformation, affecting the diffusion of Fe atoms both at the GB and in adjacent positions. This results in new diffusion pathways but with higher diffusion barriers, unlike for the $\Sigma 3$ GB. These results indicate that the presence of hydrogen rigidifies the direct GB interface layers while allowing more atoms to be active for the $\Sigma 37$ GB. This provides a microscopic basis to support the existence of competing mechanisms compatible with either plasticity (such as hydrogen enhanced localized plasticity—HELP) or energy-dominated (hydrogen enhanced decohesion mechanism—HEDE) embrittlement, with the relative importance of these mechanisms determined by the local geometry of the GBs. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-d9bc26dea26546e699e6fe9fa2708d462025-01-31T13:10:58ZengIOP PublishingJPhys Materials2515-76392025-01-018101501210.1088/2515-7639/ada994Understanding the influence of hydrogen on BCC iron grain boundaries using the kinetic activation relaxation technique (k-ART)Aynour Khosravi0https://orcid.org/0000-0002-9364-4758Jun Song1https://orcid.org/0000-0003-3675-574XNormand Mousseau2https://orcid.org/0000-0003-0575-7590Département de Physique and Regroupement québécois sur les matériaux de pointe, Université de Montréal , Montréal, CanadaDepartment of Mining and Materials Engineering, McGill University , Montréal, CanadaDépartement de Physique and Regroupement québécois sur les matériaux de pointe, Université de Montréal , Montréal, CanadaHydrogen embrittlement (HE) poses a significant challenge to the mechanical integrity of iron and its alloys. This study explores the influence of hydrogen atoms on two distinct grain boundaries (GBs), $\Sigma37$ and $\Sigma3$ , in body-centered-cubic (BCC) iron. Using the kinetic activation relaxation technique , an off-lattice kinetic Monte Carlo approach with an EAM-based potential, extensive catalogs of activated events for atoms in both H-free and H-saturated GBs were generated. Studying the diffusion of H, we find that, for these systems, while GB is energetically favorable for H, this element diffuses more slowly at the GBs than in the bulk. The results further indicate that the $\Sigma 3$ GB exhibits higher stability in its pure form compared to the $\Sigma 37$ GB, with notable differences in energy barriers and diffusion behaviors. Moreover, with detailed information about the evolution landscape around the GB, we find that the saturation of a GB with hydrogen both stabilizes the GB by shifting barriers associated with Fe diffusion to higher energies and reducing the number of diffusion events. For the $\Sigma 37$ GB, the presence of hydrogen causes elastic deformation, affecting the diffusion of Fe atoms both at the GB and in adjacent positions. This results in new diffusion pathways but with higher diffusion barriers, unlike for the $\Sigma 3$ GB. These results indicate that the presence of hydrogen rigidifies the direct GB interface layers while allowing more atoms to be active for the $\Sigma 37$ GB. This provides a microscopic basis to support the existence of competing mechanisms compatible with either plasticity (such as hydrogen enhanced localized plasticity—HELP) or energy-dominated (hydrogen enhanced decohesion mechanism—HEDE) embrittlement, with the relative importance of these mechanisms determined by the local geometry of the GBs.https://doi.org/10.1088/2515-7639/ada994defectsdiffusiongrain boundariesdiffusion & dynamics of clustershydrogen embrittlement |
| spellingShingle | Aynour Khosravi Jun Song Normand Mousseau Understanding the influence of hydrogen on BCC iron grain boundaries using the kinetic activation relaxation technique (k-ART) JPhys Materials defects diffusion grain boundaries diffusion & dynamics of clusters hydrogen embrittlement |
| title | Understanding the influence of hydrogen on BCC iron grain boundaries using the kinetic activation relaxation technique (k-ART) |
| title_full | Understanding the influence of hydrogen on BCC iron grain boundaries using the kinetic activation relaxation technique (k-ART) |
| title_fullStr | Understanding the influence of hydrogen on BCC iron grain boundaries using the kinetic activation relaxation technique (k-ART) |
| title_full_unstemmed | Understanding the influence of hydrogen on BCC iron grain boundaries using the kinetic activation relaxation technique (k-ART) |
| title_short | Understanding the influence of hydrogen on BCC iron grain boundaries using the kinetic activation relaxation technique (k-ART) |
| title_sort | understanding the influence of hydrogen on bcc iron grain boundaries using the kinetic activation relaxation technique k art |
| topic | defects diffusion grain boundaries diffusion & dynamics of clusters hydrogen embrittlement |
| url | https://doi.org/10.1088/2515-7639/ada994 |
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