EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

In this work, we apply atomistic simulations to consider hydrogen behavior in Fe in presence of the given lattice distortions, namely, defects or lattice expansion/compression due to applied stresses. Simulations are based on two different interatomic potentials describing Fe-H system: the one from Ramasubramaniam et al [1] and the other one developed by the authors of the current work [2]. Firstly, we consider the segregation of hydrogen on typical defects of different complexity: from vacancies to grain boundaries (GBs). The reported values of segregation energies obtained for different types of grain boundaries generally agree with the existing DFT data. Moreover, performed atomistic simulations give information on several types of GBs, which, due to their complex structure and considerable model size, are usually inaccessible for ab initio modeling. High-temperature simulations of H diffusion in the presence of GBs also show that for bcc Fe hydrogen diffusion coefficient in the boundary is much lower than that in bulk. For bulk under the stress, we discuss variations in hydrogen migration barriers (at zero temperature) and compare them with the results of the finite-temperature hydrogen diffusion simulations. We see that while variations in the lattice parameter change hydrogen migration barrier, they show no significant impact on the finite-temperature hydrogen diffusion coefficients.

[1] A. Ramasubramaniam, M. Itakura, and E. A. Carter, Phys. Rev. B 79, 174101 (2009)

[2] S.V. Starikov, D.E. Smirnova, Development of new interatomic potential for atomistic simulation of defects behaviour in Fe-Cr-H ternary system, contributions to the NuMat2020 conference, DOI: 10.13140/RG.2.2.14024.9600