Effects of Alloying Elements on Twinning in Ni-Based Superalloys

Micro-twinningMicro-twinning is the major creepCreep deformation mechanismDeformation mechanisms in Ni-based superalloysNi-based superalloy at temperatures above 700 °C. Recent experiments suggest that superlattice stacking faultsStacking faults in γ′ phase may serve as the precursors to twin formation. SegregationSegregation of alloying elements to these precursors may have a significant effect on formation and extension of micro-twinsMicro-twins. Using atomistic modelingAtomistic modeling we investigate and explain the effects of Nb and Cr alloying additions on these processes. The simulation shows that Nb increases the creep resistanceCreep resistance which is mostly associated with impeding the reordering of the high energy double complex stacking faultStacking faults. Cr, on the other hand, promotes twin growth, degrading the high temperatureHigh temperature creep propertiesCreep properties. These results can help to understand the effects of elemental composition of the alloy on creep resistanceCreep resistance.