First-principles study of the effects of selected interstitial atoms on the generalized stacking fault energies, strength, and ductility of Ni

We analyze the influences of interstitial atoms on the generalized stacking fault energy (GSFE), strength, and ductility of Ni by first-principles calculations. Surface energies and GSFE curves are calculated for the 〈11〉 (111) and 〈10〉 (111) systems. Because of the anisotropy of the single crystal, the addition of interstitials tends to promote the strength of Ni by slipping along the 〈10〉 direction while facilitating plastic deformation by slipping along the 〈11〉 direction. There is a different impact on the mechanical behavior of Ni when the interstitials are located in the slip plane. The evaluation of the Rice criterion reveals that the addition of the interstitials H and O increases the brittleness in Ni and promotes the probability of cleavage fracture, while the addition of S and N tends to increase the ductility. Besides, P, H, and S have a negligible effect on the deformation tendency in Ni, while the tendency of partial dislocation is more prominent with the addition of N and O. The addition of interstitial atoms tends to increase the high-energy barrier γmax, thereby the second partial resulting from the dislocation tends to reside and move on to the next layer.