Identification of the mechanism-limiting nitrogen diffusion in metallic alloys by in situ photoemission electron spectroscopy

In situ photoemission electron spectroscopy is used to identify the mechanism limiting the thermally activated nitrogen diffusion in metallic alloys. The samples were prepared by bombarding stainless steel with a broad ion source in a high-vacuum chamber. The photoemission spectra evolution on increasing controlled oxygen partial pressure is correlated with bulk material properties. The presence of oxygen inhibits the formation of iron nitrides and gamma(N)-phase (austenitic face-centered-cubic lattice containing nitrogen), which proved to be fundamental for efficient nitrogen penetration in the alloy. (C) 2003 American Institute of Physics.