About this Abstract |
| Meeting |
2027 TMS Annual Meeting & Exhibition
|
| Symposium
|
Transmutation Effects in Materials in Fission, Fusion, and Spallation Environments
|
| Presentation Title |
Dislocation Mediated HenVm Defect-Complex Diffusion in bcc Fe |
| Author(s) |
Quanyou Zhang, Zehui Qi, Tao Liang, Siwei Chen, Steven Zinkle |
| On-Site Speaker (Planned) |
Quanyou Zhang |
| Abstract Scope |
High-temperature helium embrittlement (HTHE) severely degrades the performance of nuclear structural materials. However, the atomistic mechanisms by which helium redistributes under reactor conditions, particularly the roles of stress and dislocations, remain poorly understood. To resolve this, we combine self-evolving atomistic kinetic Monte Carlo (SEAKMC) and molecular dynamics (MD) to probe helium–vacancy (He–V) complex migration in bcc Fe under applied stress and near dislocations. We find that tensile stress up to 1 GPa only slightly reduces He–V migration barriers relative to the bulk value, whereas dislocation strain fields sharply lower helium dissociation barriers and enable fast pipe diffusion along dislocation cores. These predictions are confirmed with helium implantation experiments on Fe–9Cr alloys, which show dislocation-associated cavity growth. This work establishes dislocations, rather than external stress, as the dominant helium transport pathways, providing a mechanistic foundation for predicting and mitigating HTHE in structural alloys. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Modeling and Simulation, Nuclear Materials, Iron and Steel |