The creep-fatigue interaction has been recognized as the main failure mode of most structural components operating in the high-temperature regime. The cyclic life (N_f) usually decreases continuously with the dwell time in their interactions. However, N_f shows an abnormal change, i.e. keeps constant or slightly increases/decreases, in the present studied Nickel-based superalloy, DZ445. This means that generalized “N_f saturation” is achieved by a dynamic equilibrium between the straight single superdislocations and dislocation networks corresponding to local and homogeneous damage, respectively. The saturation appears more easily with the increasing high strain ranges. The variation in the mechanical response parameters, the damage characterizations, and the phase involutions with the increasing dwell time exhibits the low amplitude under the high strain range. The combined characteristics show that the easy occurrence of N_f saturation in the range of large deformations is obtained by increasing the local-damage. The low change rate of straight single superdislocations with the dwell time in the range of large deformation is well confirmed by the above mechanism. The parameters in the different criterion models of the cyclic-life “saturation phenomenon” unify the mechanical response and the damage mechanism soundly. The work provides a new theoretical basis and guidance for the creep-fatigue safety design of high-temperature metallic materials and the establishment of dislocation-based models.

蠕变疲劳相互作用已被认为是大多数在高温状态下运行的结构部件的主要失效模式。循环寿命（N _f）通常随着它们相互作用中的停留时间而连续减少。然而，在目前研究的镍基高温合金DZ445中，N _{f显示出异常变化，即保持恒定或略微增加/减少。}这意味着广义的“N _f饱和”是通过直单超位错和位错网络之间的动态平衡来实现的，分别对应于局部和均匀损伤。随着高应变范围的增加，饱和更容易出现。随着停留时间的增加，机械响应参数、损伤特征和相位对合的变化在高应变范围下表现出低振幅。_{综合特征表明，N f}容易发生通过增加局部损伤来获得大变形范围内的饱和度。上述机理很好地证实了直单超位错在大变形范围内随停留时间的低变化率。循环寿命“饱和现象”的不同判据模型中的参数将力学响应和损伤机制很好地统一起来。该工作为高温金属材料的蠕变疲劳安全设计和基于位错模型的建立提供了新的理论依据和指导。