Hydrogen accommodation in alpha-iron and nickel

作者：Fullarton M L; Voskoboinikov R E^*; Middleburgh S C

来源：Journal of Alloys and Compounds, 2014, 587: 794-799.

DOI：10.1016/j.jallcom.2013.10.169

• Vacancy
• Hydrogen
• HxV cluster
• Ab initio calculations
• Vacancy formation energy
• Lattice contraction

Ab initio calculations have been used to study the effects of hydrogen on vacancy concentrations in alpha-Fe and Ni. The presence of H interstitials aided vacancy formation in both metals but via two different mechanisms. In alpha-Fe, trapping of H by a vacancy is favourable. However binding of further hydrogen atoms was not predicted to proceed. The thermal equilibrium concentration of H interstitials in comparison to vacancies in alpha-Fe is many orders of magnitude higher over a wide temperature range. Excessive H interstitials in solid solution facilitate vacancy formation, lowering the required energy by 0.79 eV (down to 1.41 eV). In Ni, a single H interstitial is not expected to have an impact on the vacancy population, increasing the vacancy formation energy by 0.32 eV. Two bound H interstitials however are predicted to decrease the vacancy formation energy by 0.52 eV with expected arrangement along a < 111 > direction around the vacancy. The calculations show reasonable agreement with experimental data when comparing crystal lattice contractions of the pure metals and predicted melting temperature of the Me-H alloys.

• 出版日期2014-2-25