Twinning structure of M₂₃C₆ carbide precipitated at twin-related grain boundaries in Alloy 600

Abstract

The microstructure features of carbides precipitated at twin boundary and Σ9 grain boundary (GB) in nickel-based Alloy 600 after aging at 715 °C for different time were investigated by high-resolution transmission electron microscopy. The carbides precipitated at incoherent twin boundary and Σ9 GB were identified as M₂₃C₆. The bar-like carbides grow parallel to each other and into each side of grain nearby incoherent twin boundary, while only growth into one side nearby Σ9 GB is observed. The carbides precipitated at incoherent twin and Σ9 GBs contain twins. The carbides have (1 1 1) _matrix // (1 1 1) _M23C6 orientation relationship with the nearby matrix. Based on the experimental results, the formation of twinning microstructure features in the M₂₃C₆ is discussed.

Keywords:

• M₂₃C₆
• carbides precipitation
• grain boundary
• twin-related grain boundary
• nickel-based superalloy

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant number 51301103].