Migration of vacancies, HE insterstitials and HE-vacancy clusters at grain boundaries in α-FE
The dimer method for searching transition states has been used to systematically study possible migration paths of vacancies, He interstitials and He-vacancy (He/V) clusters at Σ11<110> {323} and Σ3<110> {111} grain boundaries (GBs) in α-Fe. Vacancies trapped at the GBs diffuse along the GBs with migration energies much less than that within the perfect crystal. Long-time dynamics simulations of diffusion pathways reveal that vacancies migrate one-dimensionally along the close-packed rows in the Σ3 GB, and one-dimensionally in zigzag paths within the Σ11 GB. Also, dimer saddle point searches show that He interstitials can diffuse along the GBs with migration energies of 0.4-0.5 eV, similar to those of individual vacancies at the GBs, and the corresponding mechanisms are determined. Finally, the rate-controlling activation energy for migration of a He-divacancy cluster in the GBs determined using the dimer method is about 0.9 eV, which is comparable to the migration energy for a He-divacancy cluster in bulk α-Fe.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1328077
- Report Number(s):
- PNNL-SA-58951; DOE/ER-313/43; AT2030110
- Resource Relation:
- Related Information: Fusion Materials Semiannual Progress Report for the period Ending December 31, 2007, 43:186-191. DOE/ER-313/43
- Country of Publication:
- United States
- Language:
- English
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