Effect of helium and hydrogen synergy on vacancy migration energy in Fe-10Cr model alloy

Effect of helium and hydrogen synergy on vacancy migration energy (Emv) and microstructural evolution of Fe-10Cr model alloy were investigated by single-He, H and sequential-(He + H) ion pre-implantation and subsequent in-situ electron irradiation at different temperature. Growth rates of irradiation induced dislocation loops were experimentally measured at temperatures ranging from 573 to 773 K to calculate Emv. The loop's size increased as a function of irradiation dose. Moreover, pre-implantation with sequential-(He + H) ion showed an increase in the temperature dependence of the loop growth rate compared to implantation with single He and H. The Emv were determined to be 1.4–1.5 eV in single He and H implanted sample. In-situ electron irradiation experimental results indicated that the Emv be increased due to He and H synergy. Foil surface effect on the calculation of the migration energy has been considered also by discussing a new derivation. This synergic effect of He and H on the evolution of dislocation loop and the mobility of vacancy have been discussed. •Microstructure evolution of singe-He, H and sequential-(He+H) ion implanted Fe-Cr was observed in situ HVEM.•Vacancy migration energy was obtained by function of loops growth rate and temperature.•A new derivation was developed to consider the foil surface effect on the Em measurement.•Synergistic effect of He and H on the mobility of vacancy was discussed.