Interdiffusion in Au / Fe couples under elevated hydrogen pressures

The interdiffusion coefficients D̃ in the Au/γ-Fe two-phase and the Au/Au-37at%Fe single-phase couples have been determined under the hydrostatic pressure (HP) and hydrostatic hydrogen pressure (HHP) of 5 GPa at 1263 K. The value of D̃ in the Au-rich phase of the Au/γ-Fe couple under the HHP of 5 GPa is 4 times larger than that under the HP of 5 GPa, while the value of D̃ in the γ-Fe phase under the HHP is 50 times larger than that under the HP, implying that the concentration of vacancies injected by the HHP into the γ-Fe phase is much larger than that into the Au-rich phase. The enhancement of the interdiffusion in the Au/γ-Fe couple by the HHP of 5 GPa is attributed to the enlargement of vacancy flow from the γ-Fe phase towards the Au-rich phase in the couple.