Molecular dynamics studies of the grain-size dependent hydrogen diffusion coefficient of nanograined Fe

XY Zhou and JH Zhu and HH Wu, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 46, 5842-5851 (2021).

DOI: 10.1016/j.ijhydene.2020.11.131

Nanograined materials have much denser grain boundary (GB) networks than their coarsegrained counterparts, thereby the hydrogen (H) diffusion and trapping behaviors in nanograined materials, which are strongly influenced by GBs, may differ greatly from those in coarse-grained materials. In the present research, the grain-size dependent hydrogen diffusion coefficient in nanograined Fe is studied by theoretical analysis and molecular dynamics (MD) simulations. A theoretical model based on thermodynamics is developed. The GB-related material parameters required by the model are then obtained by fitting the MD simulation results. Finally, the grain-size dependent diffusion coefficients are compared with model predictions to evaluate the validity of the model. It is found that the trapping effect of triple junctions that usually ignored in coarse-grained materials becomes increasing important as grain size and temperature decrease. Due to the strong trapping effect of GBs in nanograined Fe, H diffusion is slowed down by the GBs. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Return to Publications page