PIII nitriding of fcc-alloys containing Ni and Cr

Face-centred cubic (fcc) alloys such as austenitic stainless steel, Ni base alloys and Co base alloys are important materials with a high corrosion resistance. Nitrogen insertion by PHI into all these alloys at moderate temperatures leads to the formation of an expanded austenite structure. A similar activation energy for the thermally assisted diffusion of about 0.75 eV was found for steel and CoCr alloys with CrN precipitates beyond 400 degrees C in both systems. However, a double layer structure was observed for CoCr, similar to Ni alloys, in contrast to a single layer for austenitic steel. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.