Elemental Hydrogen Diffusion in fcc-bcc Grain Boundaries

Hydrogen-rich operating environments and processing conditions have led to a manufacturability problem of environmentally-assisted cracking due to hydrogen embrittlement. In the case of materials fabricated by additive manufacturing, the increased occurrence of dislocations and vacancies have been theorized to correspond to an increase susceptibility to hydrogen embrittlement. A component of mitigating hydrogen embrittlement is a fundamental understanding of the hydrogen-material interactions at the most impactful structures and defects. In the following work, two approaches have been used to calculate the probabilistic behavior of hydrogen near and at grain boundaries in face centered and body centered cubic structures of FeCrNi. The first approach employs high-throughput ab initio calculations coupled with determination of transition states via the embedding energy. The second utilizes a classical atomistic forcefield based on the embedded atom method but includes a novel short-range term that enables simulation of collision cascades. The resultant diffusion pathways and potential barriers can be used to guide engineering applications of the alloys.