Compressive behavior and elastic properties of Ni-based γ/γ’ ternary model superalloys: First-principles calculations and rule of mixtures predications

Abstract

Using a total-energy method based on the density functional theory (DFT), the strengthening effects of Mo, Ta, W, and Re on the ideal uniaxial compressive strength (σICS) and elastic properties of Ni-based single-crystal (NBSC) superalloys were systematically investigated using a model consisting of γ/γ′ multilayers. The ability of the ternary alloying elements to enhance σICS, the elastic constants, and elastic modulus were in the order: Re > W > Mo > Ta. Our calculated elastic properties were consistent with reported experimental results for commercial superalloys (e.g., CMSX-4 and TMS-26), as well as with other reported computational results. Furthermore, the charge density difference of the γ/γ′ ternary alloys during compressive deformation were analyzed to understand the strengthening mechanisms of the alloying elements. The mechanical properties of the γ/γ′ ternary model alloys were predicted by modifying the first-order rule of mixtures (ROM) with the alloying element concentrations, and the determined values were in close agreement with the results of the first-principles calculations.