First-principles study on the structural, mechanical and electronic properties of δ and γ″ phases in Inconel 718

The structural, mechanical and electronic properties of δ phase and γ″ phase in Inconel 718 superalloy have been studied by using first-principles based on density functional theory. The structures of both the phases are optimized and the calculated results are in good agreement with the experimental results. The formation energies of δ phase and γ″ phase are calculated to be −1.48 eV per atom and −0.69 eV per atom, respectively. This suggests that δ phase is thermodynamically more stable than γ″ phase. The relatively high values of C11–C12 and B/G indicate that both the phases are hard and have good ductility. The bonding character has been analyzed based on the partial density of states, Mulliken population and charge density distribution.