The interaction of hydrogen with the interface of AI2O3 particles in iron

A mathematical model to calculate the trap binding energy and trap density is suggested considering the theories of hydrogen trapping and hydrogen retrapping. When iron containing 2.0 wt pct Al₂O₃ is heated with a uniform heating rate of 3 K-min^-1, a hydrogen peak is observed at 853 K in the evolution ratevs temperature plot. This is due to hydrogen evolution from the Al₂O₃/lattice interface. The trap activation energy and trap binding energy of hydrogen at the Al₂O₃/lattice interface are estimated as 79 kJ ⋅ mol^-1 and 71.4 kJ ⋅ mol^-1, respectively, fitting experimental data to the model. This indicates that the Al₂O₃/lattice interface acts as an irreversible trapping site for hydrogen. By combining the trap binding energy and trap activation energy, the energy level of hydrogen around the Al₂O₃/lattice interface is suggested. The saddle point energy of hydrogen at Al₂O₃/lattice interface, 7.56 kJ ⋅ mol^-1 is nearly equivalent to the activation energy for hydrogen diffusion through a normal lattice, 6.9 kJ ⋅ mol^-1. Formerly Graduate Student, Korea Advanced Institute of Science and Technology.