Correlation of the properties of quasi-ternary Ni-based superalloys computed from DFT to elemental properties enabling predictions on the behavior of metallic alloying elements

Abstract Research on multicomponent superalloys derived from Ni 3 Al shows that certain elemental additions congregate at the boundary of the γ / γ ′ interface while certain others partition into either the γ or the γ ′ phases. Such microstructural features have a strong bearing on the performance of the superalloy. However, no established correlations exist as of now, that can help predict such a behavior. The present work addresses this issue by examining the properties of the quasi-ternary alloys of Ni 3 Al and brings out correlations to selected lumped parameters related to the elemental properties. Computation of thermodynamic properties of 11 alloys of quasi-ternary Ni 24 Al 7 X system was carried out from first principles using Wien 2k and Gibbs2 code on a supercell constructed with 32 atoms. Elements X substituted at the Al site are selected from the information derived from the literature. Systematic variations are shown to occur in compressibility and heat of formation Δ H of the alloys with average electron concentration, elemental radii and/or electronegativity of the constituent elements in the alloys. Analysis of the data computed for a supercell on Δ H of quasi-ternary Ni 31 X alloys of Ni (the γ phase) and the Δ H of Ni 24 Al 7 X alloys (the γ ′ phase) explains the possible reason for the enrichment of elements like Re and W at the γ / γ ′ interface. Trends in the observed correlations correctly predict the experimental observations on alloying effects reported from spectroscopic studies on quasi-ternary alloys of Ni 3 Al. The scope of predicting alloying behavior based on basic elemental properties gains significance in the design of superalloys.