Self-diffusion in high purity Fe-50 mass%Cr alloy

Tracer self-diffusion coefficients of ⁵¹Cr and ⁵⁹Fe in a high purity Fe-50 mass%Cr alloy have been determined in the temperature range between 923 and 1273 K by use of the sputter-microsectioning technique. A linear Arrhenius line has been observed for each self-diffusion across the α-σ phase transformation temperature 1103 K, which is consistent with the suppression of the σ phase formation by purification. The Arrhenius equations can be expressed by D_Cr = 0.54 × 10^-4 exp(-251 kJ mol^-1/RT)m² s^-1 and D_Fe = 0.30 × 10^-4 exp(-243 kJ mol^-1/RT) m² s^-1. The activation energies for the self-diffusion of Cr and Fe by the present work are much lower than 293 and 312 kJ mol^-1 determined previously by Paxton et al. in the temperature range from 1223 to 1523 K, respectively.