Pore-induced defects during thermo-mechanical fatigue of a fourth-generation single crystal superalloy

Comparable investigation of pore-induced defects during in-phase (IP) and out-of-phase (OP) thermo-mechanical fatigue (TMF) were conducted on fourth-generation single crystal superalloy. It was discovered that recrystallizations and deformation twins would take shape near micro-pores at IP and OP cycling, respectively. High-resolution observation uncovered that the increasing a/6(112) twinning dislocations and more frequent activation of (112){111) viscous slipping during OP-TMF accounted for twinning nucleation. Atom-scale mapping additionally disclosed the dual effect of Re, Co, and Cr in facilitating twinning formation and impeding of partial dislocations movement. It was deemed that the accumulation of pore-induced twins caused the premature fracture of alloy during OP-TMF.

Automated summary

Comparable investigation was conducted on pore-induced defects during in-phase (IP) and out-of-phase (OP) thermo-mechanical fatigue (TMF) in fourth-generation single crystal superalloy. It was found that recrystallizations and deformation twins formed near micro-pores in IP and OP cycling, respectively. High-resolution observation revealed that the increase of a/6(112) twinning dislocations and the more frequent activation of (112){111) viscous slipping during OP-TMF contributed to twinning nucleation. Atom-scale mapping further showed the dual effect of Re, Co, and Cr in promoting twinning formation and hindering partial dislocations movement. The accumulation of pore-induced twins was considered to cause premature fracture of the alloy during OP-TMF.