Abstract: A model system consisting of Ni[001](100)/Ni₃Al[001](100) multi-layers are studied using the density functional theory in order to explore the elastic properties of single crystal Ni-based superalloys. Simulation results are consistent with the experimental observation that rafted Ni-base superalloys virtually possess a cubic symmetry. The convergence of the elastic properties with respect to the thickness of the multilayers are tested by a series of multilayers from 2$\gamma'$+2$\gamma$ to 10$\gamma'$+10$\gamma$ atomic layers. The elastic properties are found to vary little with the increase of the multilayer's thickness. A Ni/Ni₃Al multilayer with 10$\gamma'$+10$\gamma$ atomic layers (3.54 nm) can be used to simulate the mechanical properties of Ni-base model superalloys. Our calculated elastic constants, bulk modulus, orientation-dependent shear modulus and Young's modulus, as well as the Zener anisotropy factor are all compatible with the measured results of Ni-base model superalloys R1 and the advanced commercial superalloys TMS-26, CMSX-4 at a low temperature. The mechanical properties as a function of the $\gamma'$ phase volume fraction are calculated by varying the proportion of the $\gamma$ and $\gamma'$ phase in the multilayers. Besides, the mechanical properties of two-phase Ni/Ni₃Al multilayer can be well predicted by the Voigt-Reuss-Hill rule of mixtures.

Key words: Ni-based superalloys, Ni/Ni₃Al multilayer, mechanical property, first principles, rule of mixture