To better understand how hydrogen affects the functional and structural properties of materials, as well as its role in material degradation, we can utilize atom probe tomography (APT) to map hydrogen segregation at the nanoscale to defects and interfaces. Hydrogen's tendency to diffuse out of materials even at room temperature requires a precise process for charging materials with hydrogen isotopes and then transferring the samples under vacuum and cryogenic conditions to the APT. When this data is combined with structural analyses from transmission electron microscopy (TEM), it allows for spatially resolved mapping of hydrogen in relation to defects and interfaces in materials.

This presentation will highlight the advanced capabilities at the Pacific Northwest National Laboratory for the seamless transfer of material samples before and after hydrogen isotope charging. Transfers are conducted between a plasma-focused ion beam (Helios Hydra), an APT system (LEAP 6000XR), and a nitrogen-containing glovebox at both room and cryogenic temperatures. Leveraging this capability, we quantitatively analyzed the hydrogen uptake in a model FeCrNi alloy, both with and without deformation-induced defects, and differentiated between diffusible and trapped hydrogen within the microstructure. This unique capability is also being extended to examine hydrogen segregation in complex oxides and platinum group element catalysts, allowing us to identify the tendency of hydrogen to segregate to defects and interfaces.