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 delta phase and gamma '' 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 delta phase and gamma '' phase are calculated to be -1.48 eV per atom and -0.69 eV per atom, respectively. This suggests that delta phase is thermodynamically more stable than gamma '' phase. The relatively high values of C-11-C-12 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. (C) 2010 Elsevier B.V. All rights reserved.