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研究了定向凝固钴基高温合金DZ40M700℃和900℃缺口疲劳性能及疲劳断口。结果表明，DZ40M合金具有较高的抗高温缺口疲劳破坏能力，700℃和900℃缺口疲劳强度分别为285MPa和203MPa，且表现出低的疲劳缺口敏感性，700℃和900℃疲劳缺口敏感度仅为0．146和0．153。在交变载荷作用下，700℃缺口疲劳裂纹是以小平面方式、沿着｛111｝滑移面扩展；而900℃缺口疲劳裂纹是在交变载荷和环境氧化综合作用下，开始沿着｛001｝解理面，随后以疲劳辉纹方式扩展。DZ40M合金的独特显微组织结构和优异的静态力学性能（特别是塑性）是其具有良好的抗高温缺口疲劳性能的主要原因。
The fatigue properties and fatigue fracture of DZ40M700 ℃ and 900 ℃ for directional solidification cobalt-based superalloy were studied. The results show that the DZ40M alloy has a high capability of resistance to high temperature fatigue damage. The fatigue strength of notch at 700 ℃ and 900 ℃ is 285MPa and 203MPa, respectively. The fatigue sensitivity of DZ40M alloy is low at 700 ℃ and 900 ℃ 0.146 and 0.153. Under alternating load, the notched fatigue crack at 700 ℃ expands along the {111} slip plane in the form of facet; however, the fatigue crack at 900 ℃ is caused by the combination of alternating load and environmental oxidation, 001} cleavage plane, followed by fatigue graining. The unique microstructure and excellent static mechanical properties (especially plasticity) of DZ40M alloy are the main reasons for its good fatigue resistance against high temperature.