Nano-twinning in a precipitate strengthened Ni-based superalloy

SY Yuan and ZH Jiang and JZ Liu and Y Tang and Y Zhang, MATERIALS RESEARCH LETTERS, 6, 683-688 (2018).

DOI: 10.1080/21663831.2018.1538021

Twinning has been found to be a dominate mechanism in the 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 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. IMPACT STATEMENTWe demonstrate that Co in the precipitates promotes a new twinning pathway featured with nucleation of one CSF on the middle plane between two separated CSFs.

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