The tracer self-diffusion of 59Fe in high-purity Fe-50wt%Cr alloy was 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 could be described by:

D (cm2/s) = 3.0 x 10-1 exp[-243(kJ/mol)/RT]

These activation energy 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