A calculation of partitional local equilibrium/negligible partitional local equilibrium boundaries in Fe–C–X systems

Local equilibrium theory has long been employed to explain the thermodynamics and kinetics of proeutectoid ferrite transformation in Fe–C–X systems. The growth kinetics of proeutectoid ferrite is decided by the diffusion behavior of the alloy element X during transformation. One of the key issues in application of this theory is the theoretical calculation and experiment determination of the partitional local equilibrium/negligible partitional local equilibrium boundary (PLE/NPLE transition temperature). In this study, we developed a simple analytic method to calculate the PLE/NPLE boundary. With this method, the PLE/NPLE boundaries in Fe–C–Mn and Fe–C–Ni systems are successfully computed and the results agree well with the formerly reported experimental results.