Effect of hydrogen on vacancy diffusion
SE Restrepo and H Lambert and AT Paxton, PHYSICAL REVIEW MATERIALS, 4, 113601 (2020).
Although it is widely recognized that even small amounts of hydrogen (H) can cause embrittlement in iron (Fe) and in (high-strength) steels, the fundamental mechanisms that cause it are not yet completely understood. To contribute to a better understanding of the behavior of H in metals, we use parallel replica dynamics (PRD) to study the effect that different amounts of atomic H have in the diffusion of a single vacancy in body-centered cubic (BCC) Fe. Using PRD we calculate the diffusion of H-vacancy complexes at temperatures and timescales that are not reachable using classical methods. Additionally, based on the PRD results and calculations of the minimum energy paths of migration, we propose a mechanism for the migration of vacancy-H complexes and formulate an analytical model for the calculation of their joint diffusivity.
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