ICAMS / Interdisciplinary Centre for Advanced Materials Simulation


Atomistic simulation of bulk and grain boundary diffusion in iron

Date: 29.06.2021
Place: 17th International Conference on Diffusion in Solids and Liquids, Malta, online

Sergei Starikov
Daria Smirnova
Matous Mrovec
Ralf Drautz

Bulk and grain boundary (GB) diffusion of atoms in Fe was investigated with use of atomistic simulation based on a new interatomic potential. The potential was designed to simulate Fe-Cr-H ternary system and, hence, allowed us to study self-diffusion and impurity diffusion processes in the framework of the united model. In addition, at the study of bulk diffusion, we combined the classical molecular dynamics modeling with spin-dynamics simulation. Such complex model revealed a strong dependence of vacancy formation energy on temperature and non-Arrhenius behaviour of the self-diffusion coefficient due to magnetic excitation at heating. Also, we found that atomic self-diffusion in symmetric tilt GBs is mostly driven by self-interstitial atoms. On the other hand, in general GBs, atoms diffuse predominantly via an exchange mechanism that does not involve a particular defect but is similar to diffusion in liquid. Most observed mechanisms lead to a significant enhancement of self-diffusion along GBs compared to diffusion in the bulk Fe. It is interesting to note that we obtain the opposite trend at study of hydrogen diffusion: for hydrogen, bulk mobility is much higher than mobility along the GBs. The results of simulations are verified by comparison with the available experimental data.

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