Nucleation of He Bubbles at Grain Boundaries of α-Fe
The formation of He bubbles in bulk or at grain boundaries (GBs) has major consequences for the structural integrity of first-wall materials. To gain insight into He effects, the accumulation of He atoms and nucleation of He bubbles in a Σ3<110>{112} GB of α-Fe is being studied using molecular dynamics with our newly developed Fe-He potential [1]. It is found that the accumulation of He atoms, the formation of He bubbles, and the evolution of the GB structure all depend on the He concentration and temperature. When a He concentration of 1% is introduced within the GB region at temperatures higher than 600 K, small He clusters are formed, and a few Fe self-interstitial atoms (SIAs) are emitted from the He clusters. The SIAs easily migrate to the nearby atomic planes and form <111> crowdions. At a He concentration of 5%, a few large He clusters are found, in platelet form, and dislocations are also formed at the peripheries of these large He clusters. At 10% He concentration the atomic structure of the GB is significantly changed due to the formation of large He clusters, and the large number of SIAs that are emitted can rearrange to form an extra atomic plane within the GB, resulting in the self-healing of the deformation induced by He accumulation and the GB climbing along the [112] direction.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1328073
- Report Number(s):
- PNNL-SA-86173; AT2030110
- Country of Publication:
- United States
- Language:
- English
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