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

Research on multicomponent superalloys derived from Ni3Al shows that certain elemental additions congregate at the boundary of the gamma/gamma ' interface while certain others partition into either the gamma or the gamma ' 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 Ni3Al and brings out correlations to selected lumped parameters related to the elemental properties. Computation of thermodynamic properties of 11 alloys of quasi-ternary Ni24Al7X 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 Delta 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 Delta H of quasi-ternary Ni31X alloys of Ni (the gamma phase) and the Delta H of Ni24Al7X alloys (the gamma ' phase) explains the possible reason for the enrichment of elements like Re and W at the gamma/ gamma ' interface. Trends in the observed correlations correctly predict the experimental observations on alloying effects reported from spectroscopic studies on quasi-ternary alloys of Ni3Al. The scope of predicting alloying behavior based on basic elemental properties gains significance in the design of superalloys.