Prediction of Nitrogen Diffusivity in α-ferrite Based on Thermodynamics

A thermodynamic based equation to predict the diffusivity of nitrogen in α-ferrite was investigated in consideration of the equilibrium nitrogen concentration. The temperature-dependent jump distance calculated from the lattice parameter of ferrite was used to derive the frequency factor as a function of temperature. The calculation accuracy for nitrogen diffusivity using the proposed thermodynamic based equation was improved by comparing the calculation results using previous empirical equations based on Arrhenius type relationship with measured diffusivity of nitrogen for α-ferrite at different temperatures.