Effects of grain boundary characters on the carbide precipitation in Inconel Alloy 600

ABSTRACT

The precipitation of carbide at the grain boundary is one of the key factors that influences the resistance of intergranular corrosion. The morphology and growth mechanism of the carbides precipitated at different grain boundaries in Alloy 600 aged at 715°C for different times were investigated by transmission electron microscopy. Two types of carbides, M₂₃C₆ and M₇C₃, can be observed in the sample. The grain boundary character significantly affects the precipitation and distribution of different carbides. The face-centred cubic structured fine M₂₃C₆ has a semi-coherent orientation relationship with the matrix, and mainly precipitates at Σ3 grain boundary in all the samples, and at Σ9 grain boundary in the short-term aged samples. The large M₇C₃ has a hexagonal crystal structure, which does not have typical orientation relationship with the matrix, and precipitates at Σ9 grain boundary in the long-term aged samples, and at Σ27 grain boundary and random grain boundary in all the samples.

KEYWORDS:

• Carbide precipitation
• grain boundary character
• grain boundary engineering
• nickel based Alloy 600

Acknowledgements

The authors would like to thank Hefeng Zheng for sample preparation and TEM observation.

Disclosure statement

No potential conflict of interest was reported by the author(s ).

Data availability statement

The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.