Effect of Ru on Deformation Mechanism and Microstructure Evolution of Single-Crystal Superalloys under Medium-Temperature and High-Stress Creep

Abstract

In this work, the effect of the Ru element on the γ′-phase evolution and deformation mechanism in the fourth-generation Ni-based single-crystal superalloy was investigated. Results show that the Ru element alters the distribution coefficient of other elements in the alloy to produce reverse partitioning behavior, which leads to a difference in microstructure between 0Ru and 3Ru. The addition of Ru triggered the incubation period before the beginning of the primary creep stage, which depends on the creep temperature and stress during creep deformation. TEM results revealed that Ru addition inhibits the slip system {111}<112> at medium-temperature (760–1050 °C) and high-stress (270–810 MPa) creep, which brings a considerably low creep rate and high creep life to the Ru-containing alloy.

Lattice Rotation and Deformation Mechanisms under Tensile Loading in a Single-Crystal Superalloy with [001] Misorientation

“…This process eliminates grain boundaries that could potentially initiate cracking, resulting in single-crystal blades. Compared to equiaxed crystal cast superalloys, this significantly increases their thermal strength and resistance to thermal corrosion [ 3 , 4 , 5 ]. In addition, high-pressure turbine blades made from single-crystal superalloys are equipped with complex cooling systems and thermal barrier coatings to further enhance their high-temperature resistance [ 6 , 7 , 8 , 9 ].…”

“…However, during the actual casting process of the blades, due to factors such as alloy properties, processing conditions, and casting structure, it is difficult to ensure that the principal stress axis of the blade is perfectly aligned with the [001] orientation of the single crystal, often resulting in deviations. As turbine inlet temperatures increase and single-crystal superalloys evolve, the incorporation of more refractory elements characterized by low diffusion coefficients complicates the control of the crystal orientation of single-crystal blades [ 4 , 17 , 18 ]. In practical engineering applications, blades that deviate from the [001] orientation by up to 15° are generally considered acceptable, reflecting a compromise between casting difficulties and performance requirements.…”