First-Principles Study on Interfacial Bonding Characteristics and Tensile Deformation Behavior of Ni (001)/Ni₃Al (001) in K418 Superalloy

In order to theoretically explore the interfacial bonding properties between the main phase (γ) and the second precipitated phase (γ') in K418 superalloy formed by direct laser deposition. First-principles calculation is utilized to study the adhesion work, interfacial energy, electronic structure, bonding properties, and tensile properties between γ phase (Ni (001)) and γ' phase (Ni₃Al (001)). The results show that the interface energy of the NiAl-center (0.35–1.19 J m⁻²) is the smallest and therefore it is with the highest interface bonding strength. The electronic analysis suggests that strong Ni-Al covalent and ionic bonds as well as Ni-Ni metal bonds at the interface of the NiAl-center model are formed with the appearance of obvious orbital hybridization. The yield strength of the NiAl-top model reaches up to 19.38 GPa under the uniaxial tensile test, which is further increased when doped with those atoms of Re, Ta, and W, up to 20.38, 20.42, and 20.93 GPa, respectively. A fundamental understanding is presented here for the design of superalloys.