The diffusion of Au in γ-Fe at 1263 to 1653K under 0.1MPa Ar, and at 1207 to 1351K under 3 to 5GPa H2, was determined by relating the interdiffusion coefficients in single-phase Fe/Fe-Au couples using the Darken-Manning relationship. The value of DAu in γ-Fe under 5GPa H2 was 2 to 3 times larger than that under 0.1MPa Ar. The temperature dependence of DAu in γ-Fe under 0.1MPa Ar and under 5GPa H2 could be described by:

D (m2/s) = 8.1 x 10-5 exp[-290(kJ/mol)/RT]

and

D (m2/s) = 1.4 x 10-3 exp[-310(kJ/mol)/RT]

respectively. The value of the activation energy under 5GPa H2 was 20kJ/mol higher than that under 0.1MPa Ar, whereas the value of the pre-exponential factor under 5GPa H2 was 17 times higher than that under 0.1MPa Ar. The enhancement of the diffusion under 5GPa H2 was attributed to a high value of the activation entropy.

Y.Yamazaki, Y.Iijima, M.Okada: Acta Materialia, 2004, 52[5], 1247-54