Atomistic simulations of the interactions of helium with dislocations in nickel

• Helium has a negative binding energy on the compression side of the edge dislocation and positive on the tension side.
• Interstitial Helium has the strongest interaction with edge dislocations among the four investigated dislocations.
• Helium-dislocation interactions depend on both the direction of approach (compression versus tension side) and the positions of Helium relative to the strongest binding energy sites of the extended edge dislocation.

The interactions of He with four dislocation types in face-centered-cubic (fcc) Ni are investigated by molecular dynamics simulations using an embedded-atom method (EAM) model. The binding energies of He in and near the cores of different dislocation types were calculated. Interstitial He has the strongest interaction with edge dislocations among the four investigated dislocations. Moreover, He has a negative binding energy on the compression side of the edge dislocation and positive on the tension side. Further calculations suggest that the attractive or repulsive natures of the He-dislocation interactions depend on both the direction of approach (compression versus tension side) and the positions of He relative to the strongest binding energy sites of the extended edge dislocation. The dependence may result in dislocation pinning via the character of the short-range interactions between interstitial He and neighboring Ni atoms.