Phase analysis of a nitrogen implanted CrNi 18.9 steel: A cems-study

Conversion Electron Mössbauer Spectroscopy (CEMS) has been used to study the modified structure of the near surface region of a nitrogen implanted austenitic X10CrNiTi18.9 steel. The implantation dose was varied from 2 to 8*10¹⁷N⁺/cm² using an implantation temperature of 200°C and an ion energy of 100 keV. The (γ/a′)-ratio in the near surface region of the untreated material was changed by electropolishing and mechanical polishing of the surface. The results of the spectra are discussed in terms of nitrogen solid solution in the case of low nitrogen doses and precipitation of Fe-nitrides (ε-Fe₂N, ε-Fe_2+xN) with increasing implantation dose. Phase transformations referring to the Fe-nitrides and the (γ/a′)-ratio are observed with increasing nitrogen content.