Temperature dependence of element partitioning in rhenium and ruthenium bearing nickel-base superalloys

The partitioning behaviour of alloying elements between the γ and γ′ phase in nickel-base superalloys with systematically varied contents of rhenium and ruthenium was investigated in the temperature range between 850 °C and 1300 °C. Ruthenium promotes a reverse partitioning of rhenium to the γ′ phase. This reverse partitioning is found over the whole temperature range up to γ′ solvus temperature. It is caused by an increased solubility of rhenium in the γ′ phase when ruthenium is present.

Research highlights▶ The preference of rhenium to partition to the γ matrix in nickel-base superalloys can be reduced by the addition of ruthenium (reverse partitioning). ▶ Reverse partitioning is caused by an increased solubility of rhenium in the γ′ precipitate phase. ▶ Reverse partitioning of rhenium is found at temperatures up to the γ′ solvus temperature.