It was shown that there was a correlation between the C diffusion coefficient and the activity coefficient of C, in austenitic Ni-Fe-Cr alloys, that could be described by:

D = D (Ni)[/Ni]0.55

where D(Ni), in m2/s, was equal to 8.7 x 10-5exp[-159.0(kJ/mol)/RT] and was close to the measured value of the C diffusion coefficient in Ni.

J.Cermák, J.Sopoušek, K.Stránský: Scripta Metallurgica et Materialia, 1993, 29[12], 1581-5