[SY-N4] Symposium N-4

[SY-N4] On the effect of hydrogen on vacancy diffusion

^○Sebastian Echeverri Restrepo¹, Anthony T Paxton² (1.Department of Metallic Materials & Ceramics, SKF, Netherlands, 2.Department of Physics, King's College London, UK)

Although it is widely recognised 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 fundamental behaviour of hydrogen in metals, in the present work we used parallel replica dynamics (PRD) to study the effect that different amounts of atomic H have in the diffusion of a single vacancy in body centred cubic (BCC) Fe. Using PRD we calculated, for the first time, the diffusion of hydrogen vacancy complexes at temperatures and time scales that are not reachable using classical methods. These calculations showed that the diffusivity of a vacancy-H complex is not only dependent of the migration barriers, but also that the addition of one H atom reduces the diffusivity of a vacancy in BCC Fe and the subsequent addition of more H atoms has the opposite effect.