Numerical simulation of nitrided layer growth and nitrogen distribution inepsilon-Fe2-3N, gamma '-Fe4N and alpha-Fe during pulse plasma nitriding ofpure iron

The surface phase constitution and the kinetics of layer growth in pure iro n pulse plasma nitrided at 520 degrees C for different times were systemati cally studied, and the relative expressions of the nitrogen concentration p rofiles in nitrided layers have been deduced. The results show that the nit rided layer consists of epsilon-Fe2-3N (epsilon), gamma'-Fe4N (gamma') and alpha-Fe (alpha) phases, and its growth in thickness follows a parabolic la w. In addition, the growth of a compound layer and diffusion layer and the nitrogen concentration distribution in the nitrided layers can be precisely predicted by employing the mathematical models obtained.