Identification of Mo-Rich M23C6 Carbides in Alloy 718

In the present study, we systematically identify and characterize a (Nb, Mo)-rich M23C6 type of M23C6 carbide with a lattice parameter of 1.094 nm in alloy 718 for the first time using a combination of selected area electron diffraction pattern and powder X-ray diffraction analysis. The time-temperature-precipitation diagrams of the precipitates in both annealed and strained conditions are obtained by particle analysis using an automated scanning electron microscopy method. (Nb, Mo)-rich M23C6 carbides first precipitate after 24 hours at 1223 K (950 °C) annealing, while they form after 10 minutes at 1273 K (1000 °C) in the strained condition. This correlates with the excess dislocations produce during deformation.