Temperature dependence of self-diffusivities in B2-type intermetallic compounds

Temperature dependence of the self-diffusivities in B2-type intermetallic compounds has been investigated. The self-diffusivities plotted against the inverse of temperature normalized by the solidus temperatures, T^f, show that the activation energy, Q, is related to T_f by Q = (19±8)RT_f^B2 J/mol, and the pre-exponential factor, D₀, is in a certain range, D₀ = 10^-2 to approximately 10^-6 m²s^-1. However, the results of CuZn, which have the order-disorder transformation below solidus temperature, are out of range of a large number of data. The hypothetical T₀ temperature between the ordered and liquid phases, T₀^B2, is evaluated from thermodynamic consideration, which reveals that the temperature dependence of the self-diffusivity of CuZn replotted against T₀^B2/T shows a tendency similar to that of other B2-type intermetallic compounds. The relationship between the activation energy of self-diffusion and the enthalpy of fusion of the ordered phase is also discussed.