(The) effects of vacancies on the hydrogen trapping in pure iron at ambient temperature

Abstract

The effects of vacancies as trapping sites of hydrogen in pure iron were studied by time lag measurements based upon gas phase charging and electrochemical detecting method at 19℃. Specimens were oil quenched from 1400℃, followed by annealing at 80℃ and 120℃ for various times to remove vacancies only. Input hydrogen fugacity was controlled by various mixtures of $H_2$ and $N_2$ gas. The values of diffusivity increased as vacancies were annealed out. Full annealed specimen showed no remarkable change of lattice solubility as the input hydrogen pressure was varied. The trap density and trap binding energy of hydrogen with lattice vacancy were found to be $4.0×10^{-1}(mol/㎥)$ and -55(KJ/mol), respectively. These results indicate that vacancies may act as deep trap sites.