Effects of local structure on helium bubble growth in bulk and at grain boundaries of bcc iron: A molecular dynamics study
- Univ. of Electronic Science and Technology of China, Chengdu (China); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Univ. of Michigan, Ann Arbor, MI (United States)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Univ. of Electronic Science and Technology of China, Chengdu (China)
- China Academy of Engineering Physics, Mianyang (China)
The nucleation and growth of helium (He) bubbles in the bulk and at Σ3 <110> {112} and Σ73b <110> {661} grain boundaries (GBs) in bcc iron have been investigated using molecular dynamics simulations. The results show that a 1/2 <111> {111} dislocation loop is formed with the sequential collection of <111> interstitial crowdions at the periphery of the He cluster and is eventually emitted from the He cluster. Insertion of 45 He atoms into a He cluster leads to the formation of a 1/2 <111> dislocation loop in Σ3 GB. It is of interest to notice that the transition of a dislocation segment through the GB leads to the formation of a step at the GB plane following the loop formation, accounting for the formation of a residual GB defect. A 1/2 <111> loop, with a {110} habit plane, is emitted with further increase of the He bubble size in the Σ3 GB. In contrast, the sequential insertion of He atoms in Σ73b GB continuously emits self-interstitial atoms (SIAs), but these SIAs rearrange at the core of the inherent GB dislocation, instead of forming a dislocation loop, which leads the GB dislocation to propagate along the [1¯1¯ 1 2] direction. In the bulk and Σ3 GB, the He bubble exhibits three-dimensionally spherical shape, but it forms longitudinal shape along the dislocation line in the Σ73 GB, a shape commonly observed at GBs in experiments.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1213011
- Report Number(s):
- PNNL-SA-111327; AT2030110
- Journal Information:
- Acta Materialia, Vol. 97, Issue C; ISSN 1359-6454
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
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