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.