Nitrogen diffusion through cementite layers

Marc Nikolussi (1) , Andreas Leineweber (2) , Eric Jan Mittemeijer (3)

1 Department Mittemeijer
2 Department Mittemeijer
3 Max Planck Institute for Metals Research

Massive cementite layers with a time-dependent thickness were grown on ferrite substrates by nitrocarburising in a dedicated NH3/H2/CO/N2 containing gas atmosphere at 783 K, 823 K and 843 K. Nitrogen diffusion through the cementite layer into the ferrite substrate took place in conjunction with growth of the cementite layer; a significant, i.e. measurable solubility of nitrogen in cementite was not observed. The nitrogen concentration-depth profiles in the substrate, underneath the growing cementite layer, were quantitatively determined using a calibrated microhardness-measurement technique. The nitrogen concentration-depth profiles were simulated on the basis of a model using an implicit finite-difference method. The simulation yielded values for the diffusivity of nitrogen through cementite, including the activation energy.

Mots clés: Physical Sciences

Marc Nikolussi, Andreas Leineweber, Eric Jan Mittemeijer. Nitrogen diffusion through cementite layers. Philosophical Magazine, 2010, 90 (09), pp.1105-1122. ⟨10.1080/14786430903292365⟩. ⟨hal-00581014⟩