Deformation mechanisms of low cycle fatigue of a fourth generation Ni-based single crystal superalloy

Ni-based single-crystal superalloys are extensively employed in turbine blades for aircraft and industrial gas engines. The blades are subjected to complex thermal and stress im-pacts during service, which may cause sudden low-cycle fatigue damage and subsequent flight accidents. To investigate the relationship between the microstructure and me-chanical properties, fatigue-damaged microstructures are compared under cyclic defor-mation at 800 and 900 degrees C using combined electron microscope characterizations. With an increase in temperature, the deformation is more concentrated in the y matrix channels and the cyclic deformation behaviors stabilizes, whereas cutting the y' phase becomes difficult with decreasing slip bands. In addition, the significance of interfacial dislocation networks in enhancing cyclic stability and hindering cyclic tension-compression asym-metry is discussed.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

In this study, the fatigue-damaged microstructures of Ni-based single-crystal superalloys were compared under cyclic deformation at 800 and 900 degrees C using electron microscopy. The relationship between microstructure and mechanical properties was investigated, and it was found that with increasing temperature, deformation was more concentrated in the y matrix channels and cyclic deformation behavior stabilized. Additionally, the importance of interfacial dislocation networks in enhancing cyclic stability and hindering cyclic tension-compression asymmetry was discussed.