Surface Mössbauer analysis of 38NCD4 steel ion implanted with nitrogen

Abstract

Surface Mössbauer measurements have been carried out for 38NCD4 steel samples, ion implanted with nitrogen at different doses and currents. It has been found that Fe-N compounds form in a wide range of compositions as aggregates in the steel matrix: from the unaffected base metal to the external surface, steel layers follow one upon the other in which first Fe2+yN with 0.3 ⩽ y < 2.7, then Fe2+xN with 0 ⩽x < 0.3, and finally austenite containing ∼10 at. % nitrogen, predominantly form. Dose decrease decreases the thickness of the above layers, while current variations produce differences in the relative amounts of the various Fe-N compounds.