Xiaoyu Chen

A novel Ni₃Al-based single-crystal superalloy was subjected to creep testing at 1200°C under applied stresses ranging from 60 to 100 MPa. The stress-related deformation mechanism was elucidated through creep performance testing and examination of microstructure evolution. The results reveal pronounced stress sensitivity, with creep life decreasing from 360.5 h to 22.6 h as the stress increased from 60 to 100 MPa. Meanwhile, the creep strain during the primary creep stage rises from 0.59% to 1.68%. In contrast, during the steady-state creep stage, a decrease in applied stress from 100 MPa to 60 MPa leads to a significant reduction in the minimum creep rate, which drops from 2.77×10⁻⁷ s⁻¹ to 5.02×10⁻⁹ s⁻¹. This behavior is closely associated with the evolution of the interfacial dislocation network at γ/γ′ interfaces, whose spacing plays a critical role in controlling the steady-state creep rate. Throughout the tertiary creep stage, the degree of topological inversion is markedly enhanced with increasing applied stress. At the same time, a concomitant decline is observed in the number density of γ′ subgrains adjacent to the fracture surface. Under an applied stress of 60 MPa, the predominant creep mechanism is confirmed to be dislocation climb. At 100 MPa, the mechanism transitions to dislocation shearing of the γ′ precipitates. In summary, this study reveals the microstructural evolution and dominant deformation mechanisms under varying stress conditions at 1200℃, providing foundational data for the material selection of turbine blades in advanced aeroengines.

A novel Ni₃Al-based single-crystal superalloy was subjected to creep testing at 1200°C under applied stresses ranging from 60 to 100 MPa. The stress-related deformation mechanism was elucidated through creep performance testing and examination of microstructure evolution. The results reveal pronounced stress sensitivity, with creep life decreasing from 360.5 h to 22.6 h as the stress increased from 60 to 100 MPa. Meanwhile, the creep strain during the primary creep stage rises from 0.59% to 1.68%. In contrast, during the steady-state creep stage, a decrease in applied stress from 100 MPa to 60 MPa leads to a significant reduction in the minimum creep rate, which drops from 2.77×10⁻⁷ s⁻¹ to 5.02×10⁻⁹ s⁻¹. This behavior is closely associated with the evolution of the interfacial dislocation network at γ/γ′ interfaces, whose spacing plays a critical role in controlling the steady-state creep rate. Throughout the tertiary creep stage, the degree of topological inversion is markedly enhanced with increasing applied stress. At the same time, a concomitant decline is observed in the number density of γ′ subgrains adjacent to the fracture surface. Under an applied stress of 60 MPa, the predominant creep mechanism is confirmed to be dislocation climb. At 100 MPa, the mechanism transitions to dislocation shearing of the γ′ precipitates. In summary, this study reveals the microstructural evolution and dominant deformation mechanisms under varying stress conditions at 1200℃, providing foundational data for the material selection of turbine blades in advanced aeroengines.

Three Co-modified coatings with different Co content distribution were prepared by electroless plating and vapor phase aluminizing (VPA) technique on Mo-rich Ni-based single-crystal superalloy. These coatings were subsequently subjected to prolonged static oxidation tests at 1000℃ for a duration of 500 hours to reveal their oxidation behavior. The findings of this study indicated that the incorporation of Co within the coatings impeded the diffusion of Al and Mo within the infiltration layer and results in a slight decrease in the oxidation resistance of the coatings during the oxidation at 1000℃. Additionally, Co accelerated the θ-to-α Al2O3 phase transformation at the initial oxidation stage. A comprehensive analysis was conducted to elucidate the oxidation kinetics and the underlying mechanisms associated with the diffusion behavior of the aluminide coatings in the presence of varying Co concentrations.