Abstract: Creep-oxidation interaction is a critical factor affecting the long-term performance of high-temperature structural materials. To investigate the effect of oxidation on creep performance, creep tests were conducted on a nickel-based single crystal superalloy DD6 under various temperatures and stresses (980 °C/250-350 MPa and 1100 °C/140-180 MPa) in both vacuum and air environments. SEM observations and EDS analysis revealed the oxidation-induced degradation of creep performance and the spatiotemporal evolution of microstructures under vacuum and air environments. Based on these findings, a semi-phenomenological model describing the spatiotemporal evolution of microstructures was proposed, with predicted errors for the γ′ phase volume fraction and γ channel width within 7% and 15%, respectively. An oxidation-affected multilayer model reflecting physical mechanisms such as microstructure evolution and dislocation strengthening was further developed. The predicted results for creep deformation and creep life showed excellent agreement with experimental data, with the majority of creep deformation predictions falling within a ±15% prediction band, and the creep life predictions falling within a ±1.3 scatter band. This research provides a novel approach for predicting the deformation behavior of nickel-based single crystal superalloy under creep-oxidation interaction, which is crucial for assessing creep life and improving structural design of turbine blades.

Key words: Nickel-based single crystal superalloys, Creep, Microstructure evolution, Constitutive model, Oxidation-affected multilayer model