Abstract:The first-principles method based on the projector augmented wave method within the generalized gradient approximation was employed to calculate the superlattice intrinsic stacking fault (SISF) and complex stacking fault (CSF) energies of the binary Ni₃Al alloys with different Al contents and the ternary Ni₃Al intermetallic alloys with addition of alloying elements, such as Pd, Pt, Ti, Mo, Ta, W and Re. The results show that the energies of SISF and CSF increase significantly with increase of Al contents in Ni₃Al. Addition of Pd and Pt occupying the Ni sublattices does not change the SISF and CSF energies of Ni₃Al markedly in comparison with the Ni-23.75Al alloy. While addition of alloying elements, such as Ti, Mo, Ta, W and Re, occupying the Al sublattices dramatically increases the SISF and CSF energies of Ni₃Al. The results suggest that the energies of SISF and CSF are dependent both on the Al contents and on the site occupancy of the ternary alloying element in Ni₃Al intermetallic alloys.

Key words: Ni₃Al; superlattice intrinsic stacking fault; complex stacking fault; alloying element; first-principles