Kinetics of Nitrogen Diffusion in Granular Manganese

The kinetics and the influence of time on granular manganese nitriding were studied by means of a vacuum resistance furnace, X-ray diffraction technique, and LECO TC-436 oxygen/nitrogen determinator. The longer the nitriding time, the more the nitrogen pickup. Except for a trace of oxide MnO that developed, the metal manganese could thoroughly be nitrided to form Mn4N and a little ξ-phase (the stoichiometric components as Mn2N) with the nitriding time lasting. A kinetic model is developed to reveal the nitriding situation and agrees well with the experimental results.