Auger electron spectroscopy has been employed to study the diffusion of sulfur and carbon in α-iron. In the temperature range 25 to 500°C carbon preferentially segregates to the surface. From 400 to 700°C sulfur segregates to the surface while carbon is thermally desorbed. An Arrhenius analysis of the sulfur diffusion data yields an activation energy of 14.5 kcal/mol, which is consistent with a grain boundary diffusion process. The kinetics of carbon migration is complicated by the thermal desorption which makes Arrhenius analysis impossible.
