Diffusion of He Interstitial and di-He Clusters at Grain Boundaries in alpha-Fe
A systematic molecular dynamics study of the diffusion mechanisms of He interstitial and their small clusters at two representive interfaces has been carried out in a-Fe. The diffusion coefficient of a He interstitial and the effective migration energies were determined. The He atom diffuses rapidly along the sigma11 grain boundary one-dimensionally along specific directions, while it migrates one-dimensionally at low temperature, two-dimensionally at intermediate temperature and three-dimensionally at higher temperature, in the sigma3 grain boundary. The di-He interstitial cluster can migrate rapidly along the sigma3 interface at low temperatures, but not at the sigma11 interface. It has been observed that a di-He interstitial cluster can kick out a self interstitial atom (SIA) at high temperatures, forming a He2V complex. The SIA migrates rapidly near interfaces, whereas the He2V complex is immobile at the temperatures considered. This small cluster may serve as a smallest nucleation for the formation of helium bubbles at interfaces.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 984241
- Report Number(s):
- PNNL-SA-48063; AT6020100
- Journal Information:
- Journal of Nuclear Materials, 367-370(Pt. 1):446-450, Journal Name: Journal of Nuclear Materials, 367-370(Pt. 1):446-450 Journal Issue: 367-370; ISSN 0022-3115; ISSN JNUMAM
- Country of Publication:
- United States
- Language:
- English
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