The critical resolved shear stress for twinning in a modern single crystal Ni-based superalloy TMS-82

Detailed observations of the microstructural evolution were performed in single crystal superalloy TMS-82 after thermo-mechanical cycling. An interesting phenomenon shows that the area close to the fracture tends to create a lot of deformation twins, while the area far from the fracture exhibits few deformation twins. Theoretical calculations were further analyzed in an effort to clarify the critical resolved shear stress for twinning in single crystal superalloy by consideration of the special shearing mechanisms of twinning dislocations. The feature that a high density of deformation twins occurs in the area close to the fracture of superalloy TMS-82 due to the stress concentration. An interesting phenomenon was found after the thermo-mechanical cycling of single crystal superalloy TMS-82, which shows that deformation twins are prone to occurs close to the fracture region. Theoretical calculations give the critical resolved shear stress for twinning. The occurrence of a high density of deformation twins dues to the stress concentration close to the fracture region.