The thermodynamic modeling of precious-metal-modified nickel-based superalloys

Thermodynamic modeling of precious-metal-modified Ni-based super-alloys (PMMS) was performed in this study using the CALPHAD approach. With this approach, the effects of platinum-group metals (PGMs) such as platinum, iridium, and ruthenium on the properties of nickel-based superalloys and their interplay with other alloying elements were understood from a thermodynamic and phase equilibrium point of view. Thermodynamic database containing PGMs was developed on the basis of the PanNi 1 database for multi-component nickel alloys. The database was first validated with available experimental data. It was then used to understand phase stability and phase transformation temperatures, such as liquidus, solidus, and γ′ precipitation temperature, of PGM modified nickel-based superalloys. The effects of alloying elements on the formation of strengthening γ′ precipitate and their partitioning in γ and γ′ were also discussed.