Nano-twinning in a γ′ precipitate strengthened Ni-based superalloy

Abstract

Twinning has been found to be a dominate mechanism in the γ′ precipitate strengthened Ni-based superalloys during service at intermediate temperatures. Here, high-resolution transmission electron microscopy and atomistic simulations have been combined to show that the twin nucleation process can be facilitated by Co replacing a fraction of Al in the γ′ precipitates, due to the negative binding energy of Co–Co atoms. The study further reveals that the presence of Co promotes a new twinning pathway featured with nucleation of one complex stacking fault (CSF) on the middle plane in between two separated CSFs.

Keywords

• Ni-based superalloy
• stacking faults
• twinning
• atomistic simulations