Surface modification of the pure iron by the pulse plasma nitriding: Application of a kinetic model

In this work, the pulse plasma nitriding process of pure iron is modelled using a kinetic model derived from the Fick's laws. This approach based on the error function model allows to simulate the growth kinetics of a biphase configuration consisting of γ′-Fe4N1−x and ɛ-Fe2–3N iron nitrides under specified conditions. By coupling the kinetics data about the diffusivities of nitrogen in α-Fe, γ′ and ɛ phases to the thermodynamic description of the Fe-N phase diagram, it is possible to evaluate the kinetic constant at each growing phase interface, the thickness of nitrided layer, and predict the nitrogen concentration profiles. The comparison between the experimental and theoretical results shows the reliability of the simulation results.