First-principle calculation of stacking fault energies in Ni and Ni-Co alloy

Abstract

The (111) intrinsic stacking fault energy γISF in Ni and Ni-Co alloy was calculated and compared using two different ab initio methods, viz., the supercell approach and the axial interaction model (AIM), based on density functional theory. The supercell approach uses energies of crystal structure in slab geometry with and without the stacking fault. In the AIM approach, the problem is mapped to a 1D spin-model and the interaction parameters are obtained using energies for ordered structures, thus obviating the need to handle faulted structure. For elemental Ni, the calculated values of γISF from AIM and supercell approaches differ by not more than by 2%, and compares well with experimental value. For Ni-Co alloy, AIM predicts a slightly faster decrease in γISF with increasing Co concentration compared to supercell approach and experimental data. Overall, there is good agreement between the two approaches.