Binding Energetics of Substitutional and Interstitial Helium and Di-Helium Defects with Grain Boundary Structure in alpha-Fe

Journal Article · Tue Jan 21 04:00:00 EST 2014 · Journal of Applied Physics, 115:033503

DOI:https://doi.org/10.1063/1.4861719· OSTI ID:1177317

Tschopp, Mark A.; Gao, Fei; Yang, Li; Solanki, K. N.

he formation/binding energetics and length scales associated with the interaction between He atoms and grain boundaries in BCC alpha-Fe was explored. Ten different low grain boundaries from the <100> and <110> symmetric tilt sigma grain boundary systems were used. In this work, we then calculated formation/binding energies for 1 - 2 He atoms in the substitutional and interstitial sites (HeV, He2V, HeInt, He2Int) at all potential grain boundary sites within 15 °A of the boundary (52826 simulations total). The present results provide detailed information about the interaction energies and length scales of 1-2 He atoms with grain boundaries for the structures examined. A number of interesting new findings emerge from the present study. For instance, the sigma3(112) twin boundary in BCC Fe possesses a much smaller binding energy than other boundaries, which corresponds in long time dynamics simulations to the ability of an interstitial He defect to break away from the boundary in simulations on the order of nanoseconds. Additionally, positive correlations between the calculated formation/binding energies of the He defects (R > 0.9) asserts that the local environment surrounding each site strongly influences the He defect energies and that highly accurate quantum mechanics calculations of lower order defects may be an adequate predictor of higher order defects. Various metrics to quantify or classify the local environment were compared with the He defect binding energies. The present work shows that the binding and formation energies for He defects are important for understanding the physics of He diffusion and trapping by grain boundaries, which can be important for modeling He interactions in polycrystalline steels.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1177317
• Report Number(s): PNNL-SA-100253; AT6020100
• Journal Information: Journal of Applied Physics, 115:033503, Journal Name: Journal of Applied Physics, 115:033503
• Country of Publication: United States
• Language: English

Related Subjects

GRAIN BOUNDARIES
HELIUM
Helium
INTERSTITIALS
IRON
forma- tion/binding energy
grain boundaries
interstitial
iron
substitutional