The tracer self-diffusion coefficients of 59Fe in high-purity Fe-50wt%Cr alloy were determined, at 923 to 1273K, by using the sputter micro-sectioning technique. A linear Arrhenius plot, across the α-σ phase transformation at 1103K, was observed. This was consistent with the suppression of σ-phase formation by purification. The results (table 59) could be described by:

D (m2/s) = 3.0 x 10-5 exp[-243(kJ/mol)/RT]

This activation energy for the self-diffusion of Fe was much lower than the 312kJ/mol which had been reported for 1223 to 1523K.

M.Sugihara, Y.Yamazaki, S.Takaki, K.Abiko, Y.Iijima: Materials Transactions, 2000, 41[1], 87-90

Table 60

Diffusion Parameters for 59Fe in the Fe-Cr System