Abstract
In order to explore novel light-weight Co-Nb-based superalloys with excellent performance, we studied the effects of alloying elements including Sc, Ti, V, Cr, Mn, Fe, Ni, Y, Zr, Mo, Tc, Ru, Rh, Pd, Hf, Ta, W, Re, Os, Ir and Pt on the structural stability, elastic and thermodynamic properties of γ′-Co3Nb through first-principles calculations. The results of transfer energy indicate that Y, Zr, Hf and Ta have a strong preference for Nb sites, while Ni, Rh, Pd, Ir and Pt have a strong tendency to occupy the Co sites. In the ground state, the addition of alloying elements plays a positive role in improving the stability of γ′-Co3Nb compound. The order of stabilizing effect is as follows: Ti > Ta > Hf > Pt > Ir > Zr > Rh > V > Ni > W > Sc > Mo > Pd > Re > Ru. Combining the calculation results of elastic properties and electronic structure, we found that the addition of alloying elements can strengthen the mechanical properties of γ′-Co3Nb, and the higher spatial symmetry of electrons accounts for improving the shear modulus of γ′-Co3Nb compound. At finite temperatures, Ti, Ta, Hf, Pt, Ir, Zr and V significantly expand the stabilization temperature range of the γ′ phase and are potential alloying elements to improve the high-temperature stability of the γ′-Co3Nb compounds.
Highlights
With the continuous development of modern aviation industry, Ni-based superalloys cannot meet the increasing performance needs because their operating temperature is close to the melting point
It is apparent that the site preference shows regular variation according to the periodic table of the elements, i.e., the tendency of elements to occupy Co site becomes progressively stronger with increasing atomic number in each period, which is similar to the findings in the Ni3 Al phase [24]
It is apparent that the site preference shows regular variation according to the periodic table of the elements, i.e., the tendency of elements to occupy Co site becomes progressively stronger with increasing atomic system is much larger than that of a typical Ni-based superalloy [35], the γ0 /γ
Summary
With the continuous development of modern aviation industry, Ni-based superalloys cannot meet the increasing performance needs because their operating temperature is close to the melting point. Further research on Co-Nb-based superalloys properties of the alloy, which is an effective way to improve the performance defects of for of light-weight superalloys. As an emerging termined according to the site preference of transition 0metal element X basic system, the effect of alloying transition elements on the properties of γ -Co3 Nb phase onis fundamentally this basis, the structural andreport mechanical properties not clear, and therestability is little relevant on this low-density system.of tern. According to the site preference of transition metal element X in γ0 -Co Nb, and on this basis, the structural stability and mechanical properties of ternary X-substituted γ0 -Co3 Nb evaluated.and. Methods of γ0 -Co3 Nb phase against D019 phase is determined, which provides a theoretical basis for Site the development the ternary light-weight Co-based superalloy base alloy system
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