Investigation of damage mechanisms in thermomechanical fatigue of nickel-based single-crystal alloys

Thermomechanical fatigue (TMF) is essential for ensuring the safety and efficiency of various thermal engineering systems, however, the underlying damage mechanisms remain unclear. In the present work, a damage evolution model is used to quantify damage mechanisms in nickelbased single -crystal superalloy DD6. The isothermal creep -fatigue model combining the fatigue and creep damages is developed to elucidate their interactions and validated by the tensiondwelling experiments. Finally, the experimentally measured TMF damage is quantitatively decomposed into fatigue, creep and extra TMF components. Significant TMF damage in the in -phase TMF is identified, especially in the [001] specimens, potentially attributed to the non -isothermal creep or oxidation, while damage in out -of -phase TMF aligns with the spiking oxidation mechanism.