Strain localisation and failure at twin-boundary complexions in nickel-based superalloys

Zhenbo Zhang, Zhibiao Yang, Song Lu, Allan Harte, Roberto Morana, Michael Preuss

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Twin boundaries (TBs) in Ni-based superalloys are vulnerable sites for failure in demanding environments, and a current lack of mechanistic understanding hampers the reliable lifetime prediction and performance optimisation of these alloys. Here we report the discovery of an unexpected γ″ precipitation mechanism at TBs that takes the responsibility for alloy failure in demanding environments. Using multiscale microstructural and mechanical characterisations (from millimetre down to atomic level) and DFT calculations, we demonstrate that abnormal γ″ precipitation along TBs accounts for the premature dislocation activities and pronounced strain localisation associated with TBs during mechanical loading, which serves as a precursor for crack initiation. We clarify the physical origin of the TBs-related cracking at the atomic level of γ″-strengthened Ni-based superalloys in a hydrogen containing environment, and provide practical methods to mitigate the adverse effect of TBs on the performance of these alloys.

Original languageEnglish
Article number4890
Number of pages11
JournalNature Communications
Volume11
Issue number1
DOIs
Publication statusPublished - 1 Dec 2020
Externally publishedYes

Cite this