Interplay between vacancy-induced hydrogen segregation and stress-induced vacancy redistribution causing embrittlement of alpha-iron
This study proposes a novel mechanism of intergranular fracture in alpha-iron, focusing on the effects of trapped vacancies, H atoms, and their synergistic interplay under tensile strain. We present a methodology for the introduction of H into grain boundaries (GBs) resulting in a realistic distribu...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Taylor & Francis Group
2025-02-01
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| Series: | Science and Technology of Advanced Materials |
| Subjects: | |
| Online Access: | https://www.tandfonline.com/doi/10.1080/14686996.2025.2459060 |
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| Summary: | This study proposes a novel mechanism of intergranular fracture in alpha-iron, focusing on the effects of trapped vacancies, H atoms, and their synergistic interplay under tensile strain. We present a methodology for the introduction of H into grain boundaries (GBs) resulting in a realistic distribution by considering H – H interactions. Accordingly, optimal H concentrations were determined under specific environmental conditions for GBs with and without vacancy-induced segregation under zero and 2% tensile strain, respectively. Subsequently, the reduction in cohesive energy at GBs was evaluated at the optimal H concentration under these conditions. In the case of H segregation without vacancies at zero applied strain, the reduction in the cohesive energy ranged approximately from 15% to 35% for all the GB configurations. Eventually, vacancy segregation increased H concentration at the GBs, defined as vacancy-induced H segregation. The vacancy-induced H segregation resulted in a 60%–117% increase in H concentration and a 70%–80% decrease in cohesive energy at a vacancy concentration of [Formula: see text] under zero applied strain. The proposed vacancy-induced H-segregation mechanism explained the delayed fracture in steel. Furthermore, the effect of tensile strain on embrittlement was elucidated, with strain-induced vacancy redistribution and vacancy-induced H segregation synergistically promoting GB decohesion, resulting in a 73%–93% reduction in cohesive energy at the same vacancy concentration. |
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| ISSN: | 1468-6996 1878-5514 |