Re effects in model Ni-based superalloys investigated with first-principles calculations and atom probe tomography*

Abstract

The phase partition and site preference of Re atoms in a ternary Ni–Al–Re model alloy, including the electronic structure of different Re configurations, are investigated with first-principles calculations and atom probe tomography. The Re distribution of single, nearest neighbor (NN), next-nearest neighbor (NNN), and cluster configurations are respectively designed in the models with γ and γ′ phases. The results show that the Re atoms tend to entering γ′ phase and the Re atoms prefer to occupy the Al sites in γ′ phase. The Re cluster with a combination of NN and NNN Re–Re pair configuration is not preferred than the isolated Re atom in the Ni-based superalloys, and the configuration with isolated Re atom is more preferred in the system. Especially, the electronic states are analyzed and the energetic parameters are calculated. The electronic structure analyses show there exists strong Ni–Re electronic interaction and it is mainly contributed by the d–d hybridization. The characteristic features of the electronic states of the Re doping effects are also given. It is also found that Re atoms prefer the Al sites in γ′ side at the interface. The density of states at or near the Fermi level and the d–d hybridizations of NN Ni–Re are found to be important in the systems.

First-principles study of co-adsorption behavior of O2 and CO2 molecules on δ-Pu(100) surface

“…[24,25] It uses projection augmented wave (PAW) [26,27] pseudopotential method for first-principles calculation, which is an efficient plane wave pseudopotential package and widely used in the calculation of electronic structures. [28][29][30] Generalized gradient approximation (GGA) in the form of Perdew-Burke-Ernzerhof (PBE) exchangecorrelation potential is used to approximate the electron exchange correlation interactions. [31,32] There are 16, 4, and 6 valence electrons in the outer shells for Pu ion (6s 2 6p 6 5f 6 7s 2 ), C ion (2s 2 2p 2 ), and O ion (2s 2 2p 4 ), respectively.…”

Effects of Re, Ta, andWin [110] (001) dislocation core of γ/γ′ interface to Ni-based superalloys: First-principles study*

“…[19,20] A deep valley well separates the bonding and antibonding parts of X-d (X = Re, Ta, and 096101-5 W) orbital PDOS near the Fermi level, which can increase the stability of the dislocation core. [40,41] In Fig. 7, it can be seen that the hybridization between Re-Ni136 is mainly from Re-d orbital and Ni136-d orbital, because the d orbital PDOS of Re and the d-orbital PDOS of Ni136 have a peak at the same low energy level, so there is a strong d-d hybridization between Re and Ni136.…”

Molecular dynamics simulations of dopant effects on lattice trapping of cracks in Ni matrix*

“…Experiments and simulations indicated that doping superalloys with Re, Ru, Co, and W improved their mechanical properties. [18][19][20][21][22][23][24][25][26][27] Our previous work reported the lattice trapping limit increased for the Ni or Ni 3 Al cracks when Re or W was added and that W incorporation yielded much stronger effects for the Ni 3 Al cracks. [4,13,15] Other reports indicated the effect of Co on the crack propagation along the γ/γ interface was minimal.…”