Synopsis: The effects of Mn, Cr, and Ni addition on the hydrogen diffusion behavior in BCC, FCC, and HCP Fe was investigated by means of first-principles calculations. Diffusion coefficients were estimated quantitatively from the migration energy calculated by the nudged elastic band method and the vibrational energy at every stable and metastable site. The addition of Mn, Cr, and Ni to a BCC lattice has a blocking effect on hydrogen diffusion and decreases the diffusion coefficient of hydrogen. Crystal orbital Hamilton population (COHP) analysis revealed that the weakened bonding between the added element and hydrogen is the origin of the blocking effect. On the other hand, the addition of Mn, Cr, and Ni to FCC and HCP lattices resulted in the formation of hydrogen trap sites. In the FCC case, the diffusion coefficients of Fe 31 MnH, Fe 31 CrH, and Fe 32 H, showed similar values, while that of Fe 31 NiH was lower. In the HCP case, the diffusion coefficients of the three additional elements showed a decreasing trend. Based on the results of the COHP analysis, we conclude that the octahedral interstitial sites around the additional elements become trap sites in FCC and HCP Fe due to the strengthened bonding between Fe and H.
|ジャーナル||Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan|
|出版ステータス||Published - 2019 2|
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Metals and Alloys
- Materials Chemistry