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 delta 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 delta 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 delta in hydrogen induced cracking is largely attributed to its higher capacity in hydrogen adsorption, and vice versa for carbonitrides.