Research progress in effect of Ru on solidification characteristics, precipitation of topologically close-packed phases and creep property of nickel-based single crystal superalloy

Nickel-based single crystal superalloys are widely used for hot components of advanced turbine engines due to their excellent mechanical properties at elevated temperature. Ru is the symbol element of the fourth and fifth generation nickel-based superalloys. During the past decades, many efforts have been made to provide insight into the role of Ru addition in superalloys. In this paper, the research progress in the effect of Ru on the solidification characteristics, as-cast microstructures, precipitation of topologically close-packed (TCP) phases, and creep properties of nickel-based single crystal superalloy was reviewed. The effect of Ru on the solidification characteristics such as solidification path, solidification transition temperature, micro-segregation, and the solidification microstructures such as eutectic, carbide were analyzed systematically. And the reasons why the addition of Ru can inhibit the precipitation of TCP phase and improve the creep property of superalloy were emphatically studied. The composition design and optimization of Ru-containing superalloy are more challenging due to the complexity of the multi-component interaction on microstructure and properties. It was suggested that the future research on Ru-containing superalloys could be explored from the following aspects: the cause of the precipitation of the new Ru-rich phases and the method of inhibiting its precipitation, the effect of Ru addition on solidification defects, the mechanism of the TCP phases. It could provide significant guidance for the composition optimization and performance improvement of the new Ru-containing nickel-based single crystal superalloys.