With the complexity of the structure of aero-engine turbine blades, the blade wall thickness continues to decrease. It is found that when the blade wall thickness decreases to a certain extent, its mechanical properties will decline significantly. It is extremely important to study this phenomenon of a significant decline in mechanical properties caused by wall thickness. In this paper, the creep behavior of a second-generation Ni₃Al-based single crystal superalloy with different wall thicknesses and [001] orientation at 980 °C/220 MPa has been studied and compared with the creep life of Φ4 round bar. The experimental results show that the second orientation and the surface affected zone are not the main reasons for the reduction of the life of thin-walled samples under this experimental condition. By analyzing the fracture morphology and deformed microstructure of thin-walled samples with different thicknesses, it is found that the thickness debit effect of the single crystal alloy occurs since the effective stress area of the alloy changes due to internal defects and surface affected zone during the creep process. For thicker samples, the creep life of the alloy can be extended by making the samples undergo certain plastic deformation through better plastic deformation coordination ability, while for thinner samples, the plastic coordination ability is poor, and the ability to extend the creep life through plastic deformation is also weaker when the effective stress area of the alloy changes, which leads to the thinner samples being more prone to fracture.

In superalloys, topologically close–packed (TCP) phases, which contain refractory elements, usually significantly influence the mechanical properties. The current work investigates the structure and composition of the TCP phase in an Al–Mo–rich Ni–based single crystal superalloy. It is shown that after 40 h of thermal exposure, a large number of strip–like TCP phases are formed, which are enriched in Mo and Re. The structure of the TCP phase is identified as the tetragonal σ phase with the lattice parameter a being 0.93 nm and c being 0.50 nm. During the creep process, the single crystal tilts obviously and leads to orientation variation from direction. Two groups of dislocations are observed in the deformed sample. One group contains straight dislocation lines and another group contains dislocation networks. The interaction between TCP phase and dislocation in the single crystal superalloy is studied to reveal the effect of the TCP phase on the deformation behavior. During creep, the σ phase hinders the dislocation movement, which may contribute to the propagation of the cracks and the final fracture.

High temperature oxidation is considered to play an essential role in the thickness debit effect on the creep rupture life of Ni-based single crystal (SC) superalloys. In order to clarify thickness effects, thin-walled specimens of different thickness (t = 0.1, 0.3, 1.0 mm) were prepared. Cyclic and isothermal oxidation tests of a high-Al Ni-based SC superalloy IC21 were carried out at 900 °C and 1100 °C in order to study the thickness effects on the oxidation behavior and consequent microstructural degradation. Thin-walled specimens of S01-N exhibited a good oxidation resistance when the protective scale-forming elements were enough in the matrix. Specimen thickness tuned the oxidation kinetics by changing the spallation behavior but had few influences on the thermodynamics. The easier stress relief via creep deformation in thin specimens is the main reason behind this phenomenon. Moreover, the obvious temperature effects on the multilayer oxide scales caused the different thickness-related spallation behaviors. Weaker microstructural degradation appeared and was further mitigated by reduced specimen thickness. Sufficient Al content is considered to be indispensable for the formation of protective α-Al₂O₃ scale with less degradation of matrix during the high temperature oxidation of thin-walled Ni-based SC superalloy castings.

The present study systematically investigated the hot deformation behavior of GH2787 superalloy within the temperature range of 1060–1120 °C and strain rates of 0.1–10 s⁻¹. An Arrhenius-type constitutive equation was developed that accurately predicts the flow behavior, and the calculated thermal deformation activation energy Q is 364,401.19 J/mol. The hot working map was constructed based on the dynamic material model, which identified two preferred processing regions with power dissipation efficiency exceeding 0.3, and no flow instability was observed across the entire parameter range. Microstructural analysis reveals that the extent of dynamic recrystallization significantly increases with rising temperature and strain rate. Discontinuous dynamic recrystallization (via grain boundary bulging nucleation) serves as the dominant recrystallization mechanism in GH2787 superalloy during hot deformation, while continuous dynamic recrystallization (via subgrain rotation and coalescence) acts as a synergistic auxiliary mechanism, jointly driving microstructural evolution. This study provides important theoretical foundations for optimizing the hot working processes of GH2787 superalloy.