Interaction between crack and twins in TMS-82 superalloy during thermomechanical fatigue process

Thermomechanical fatigue behavior of a nickel base single crystal superalloy TMS-82 has been investigated. It was found that the micropores in the alloy tend to initiate large amounts of deformation twins and the crack causes many twins to occur during its propagation. It is postulated that these twins around the micropores or the crack are induced by the stress field of the micropores or the crack tip, respectively. A thermodynamic model is adopted linking the twin formation energy with the stress field around the crack tip, which explains the observed results with good consistency. The influencing factors for a crack to stimulate twins around it are shown by the model, which might provide possible ways to enhance the alloy's thermomechanical fatigue performance.