The effect of hydrogen and helium on microvoid formation in iron and nickel

Detection of hydrogen in neutron-irradiated nickel using positron lifetime spectroscopy

“…Our results show that the main hydrogen desorption peak is at 423 K. The hydrogen detrapping energy in the hydrogen-charged nickel specimen determined from TDS data is equal to 0.91 eV. This value is comparable to the detrapping energy of 0.98 eV for mono-vacancy bound with one hydrogen atom in nickel [20][21][22]. It is interesting to note that recent theoretical calculations based on the atom superposition method [11] and the simulations [23] show that the positron lifetime of a nickel mono-vacancy containing one hydrogen was 163 [11] and 158 ps, respectively.…”

“…The formation of nickel hydride can be observed along grain boundaries after electrochemical hydrogen charging [25]. At 373 K, hydrogen escapes from nickel vacancies due to its low detrapping energy of 0.91 eV (present work) or 0.98 eV [20][21][22]. This means that nano-voids are formed only by short-range migration.…”

The Recovery of Gas-Vacancy-Complexes in Fe Irradiated with High Energy H or He Ions

“…In the previous study, we reported that He-vacancy clusters in Ni grew after annealing above 750 C based on the annealing experiment for Ni irradiated with He ions at 300 C. 21) This can be explained by the de-trapping energy of He atoms from vacancies. According to Reed, the activation energy for migration of a He atom is 0.08 eV and the binding energy of a He-vacancy complex is 3.16 eV in Ni.…”

A review of helium–hydrogen synergistic effects in radiation damage observed in fusion energy steels and an interaction model to guide future understanding

“…Most of the microscopic experimental evidence regarding interactions of He and H with point defects suggests that He atoms are more effective for void formation than H atoms [25,26]. However, experiments have not provided a clear indication beyond several qualitative arguments of the effect of He accumulation on H and vice versa.…”