First-principles investigation of interstitial solute effects on stacking fault energies in Nickel

Interstitial elements play a complex role on shear deformation in Ni, however, current experimental techniques face limitations in observing interstitial elements distribution and their interaction with the micro-structures in Ni. In this work, first-principles calculations have been used to investigate solubility behaviors of interstitial solutes (H, B, C, N, and O) in bulk Ni with the variables of component and strain. Moreover, the solute segregation behaviors at the stacking faults and their effects on stacking fault energies have been evaluated with a focus on the H-induced localized plasticity phenomenon, while H-X solute pair competitions in Ni has also been discussed in detail. Finally, the variations of shear moduli and stacking fault energies of Ni with the presence of interstitial solutes have been evaluated and their correlation has been proposed. The results revealed a strong effect of volumetric strain on interstitial solute segregation in Ni, while stacking faults acted as potential traps for interstitial solutes. The H-induced localized plasticity has also been proved in terms of stacking fault energy. Our findings aim to contribute to the development of strategies to strengthen Ni alloys that are utilized in the complex chemical environment, thereby mitigating shear failure and enhancing the critical shear stress of Ni alloys.