温度梯度对 Ni₃Al 基单晶高温合金蠕变行为的影响

Traditionally, the creep performance of superalloys are characterized under isothermal and constant-stress conditions. However, in the service environments of aero-engines, internal cooling introduces notable through-thickness temperature gradients within turbine blade materials. Consequently, examining the creep behavior of single-crystal alloys under such temperature gradients holds considerable engineering significance. This study conducts a series of temperature-gradient creep experiments based on a Ni₃Al-based superalloy. Temperature gradients of 10⁵ K/m and 5×10⁴ K/m are imposed. The results indicate that temperature gradients exert a substantial influence on specimens creep rupture life. Specifically, compared to isothermal creep, the application of a 10⁵ K/m gradient leads to an almost 46% extension in creep life, whereas a 5×10⁴ K/m gradient results in about 30% improvement. Fractographic and microstructural analyses reveal enhanced anisotropy on the fracture surface under temperature gradients. Furthermore, the oxidation behavior varies markedly across different temperature zones: the high-temperature region exhibits a denser, thinner oxide layer, whereas the low-temperature region displays a porous, thicker oxide layer. In the 10⁵ K/m gradient specimen, the low-temperature area exhibits a rafted γ′ structure, while the high-temperature area shows a de-rafted morphology, suggesting differing strain rates between these regions.