On the role of precipitates in hydrogen trapping and hydrogen embrittlement of a nickel-based superalloy

Here we report imaging of hydrogen/deuterium concentrations in δ phase and carbonitrides, and at their interfaces with the matrix in a nickel-based superalloy using Nanoscale Secondary Ion Mass Spectrometry. It is found that δ phase attracts a higher concentration of hydrogen than the matrix during cathodic charging, while carbonitrides adsorb much less. No hydrogen segregation was observed at the interfaces. Detailed electron microscopy analysis of the H-charged samples after tensioning to failure demonstrates that the higher vulnerability of δ in hydrogen induced cracking is largely attributed to its higher capacity in hydrogen adsorption, and vice versa for carbonitrides.