On the influence of impurity atoms on self-diffusion in α-iron single crystals

Self-diffusion coefficients in single crystals of pure and alloyed α-iron were measured in the temperature range from 778, 3°c to 901°c. For the low impurity concentrations used a linear dependence of the frequency factors D o on the concentrations of oxygen and carbon dissolved on interstitial sites was found. The activation energy for all specimens, except the Fe-Cu alloy, can be given by Q = 61·3 kcal/mole ± 1·5%. Titanium and vanadium were shown to have no effect on diffusion in α-iron. For the Fe-Cu alloy in D = f (1/T) is not a linear function. The influence of impurities on the self-diffusion coefficient in α-iron is discussed in terms of free and associated vacancies.