Effect of ruthenium on γ′ precipitation behavior and evolution in single crystal superalloys

The effect of Ru on γ′ precipitation behavior and evolution in single crystal superalloys with different Ru contents were investigated by scanning electron microscopy with energy dispersive spectroscopy, 3D atomic probing, differential scanning calorimetry. The results show that the solvus of the γ′ phase decreases gradually with increasing Ru content in the alloys by casting or by the same solution and aging treatments, the alloy with a larger Ru content yields a smaller γ′ phase. The addition of Ru increases the growth rate and coarsening rate of the γ′ phase. Ru mainly distributes in the γ phase, which causes more Re and Mo partition into the γ′ phase, increasing the absolute value of mismatch and the rafting rate of the γ′ phase.