Combination of hot isostatic pressing (HIP) and rejuvenation heat treatment (RHT) technology was used to restore creep-damaged DZ125 directional solidified superalloy, and the influence of microstructure restoration on high temperature fatigue behavior of the samples was explored. The results show that the HIP+RHT process could effectively heal internal cavities and recover the degraded γ′ phase in creep-damaged DZ125 superalloy to cubic particles similar as in as-received sample. After restoration treatment, the stress concentration areas inside the sample eradicated with the healing of the internal cavities, and the fatigue source areas were limited only to near surface than initiating from inside as in the as-received and creep-damaged samples. As a result, the restored sample had higher crack initiation life and lower crack propagation rate compared to as-received and creep damaged samples. The TEM microstructure characterization near fatigue fracture showed that the restoration of the degraded γ′ phase eliminated tangled dislocation in creep damaged sample and produced evenly distributed dislocations in the γ channel with short curved line-like morphology, like the as-received sample, which effectively hindered the dislocations movement during subsequent deformation, and strengthen the fatigue resistant of alloy. Therefore, it can be concluded that the HIP-RHT process, through the combined effect of internal cavities healing and the restoration of the degraded microstructures, renders higher high temperature fatigue life than creep-damaged and even higher than as-received DZ125 superalloy.

采用热等静压（HIP）与回火热处理（RHT）技术相结合的方法，对蠕变损伤的DZ125定向凝固高温合金进行修复，探讨了显微组织修复对试样高温疲劳行为的影响。结果表明，HIP+RHT 工艺可以有效地修复内部空腔，并将蠕变损坏的 DZ125 高温合金中降解的 γ' 相恢复为与接收样品相似的立方颗粒。修复处理后，样品内部的应力集中区域随着内腔的愈合而消失，疲劳源区域仅限于近表面，而不是像原样和蠕变损坏的样品那样从内部开始。其结果，与原样和蠕变损坏样品相比，修复后的样品具有更高的裂纹萌生寿命和更低的裂纹扩展速率。疲劳断裂附近的 TEM 显微组织表征表明, 退化的 γ' 相的恢复消除了蠕变损伤样品中的缠结位错, 并在 γ 通道中产生了均匀分布的位错, 具有短曲线状形态, 像原样一样, 有效地阻碍了后续变形过程中的位错运动，增强了合金的抗疲劳性。因此，可以得出结论，HIP-RHT 工艺通过内腔愈合和退化微观结构恢复的综合作用，使高温疲劳寿命高于蠕变损伤，甚至高于原样的 DZ125 高温合金。