Reactive elements dependence of elastic properties and stacking fault energies of gamma-Ni, gamma '-Ni3Al and beta-NiAl

摘要

The reactive element effects (REEs) have been proven to improve the thermal oxidation resistance of beta-NiAl. However, their effects on mechanical properties, which are significant implications for the Ni-based superalloys substrate and beta-NiAl bond coat of thermal barrier coatings (TBCs), have not been well understood so far. In this work, the basic elastic properties, ideal strengths, and stacking fault energies of reactive elements (REs: Hf, Zr, Dy, Y, La) doping gamma-Ni, gamma'-Ni3Al, beta-NiAl systems have been calculated using the first-principles method. The elastic properties results suggest that all five REs can enhance the ductilities of gamma-Ni, beta-NiAl, and gamma'-Ni3Al, of which La performs best. More interesting, the complicated stacking fault (CSF) and anti-phase boundary (APB) energies of gamma-Ni and beta-NiAl decrease with the addition of REs in order of La > Y(Dy)>Zr > Hf, showing a totally opposite trend to that of commonly accepted the REEs on oxidation. The significant charge density redistributions could explain the physical origin of the improvement of plastic deformation ability for beta-NiAl. This work gives insight into the mechanism of RE effects on the ductility and strength of gamma-Ni, gamma'-Ni3Al, beta-NiAl materials, providing theoretical guidance for Ni-based superalloys design via a combinational analysis of bond topology and electronic structure. (C) 2020 Elsevier B.V. All rights reserved.