Chemical state of ion-implanted nitrogen in Fe18Cr8Ni steel

Abstract

Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS), in conjunction with ion milling, were used to determine the chemical state of nitrogen implanted at relatively high doses (1016–1018/cm2) into type-304 steel. Nitrogen atoms were bonded in the nitrided state, at all doses, according to both AES and XPS. As the nitrogen concentration increased, the lineshape of the Cr MVV Auger spectra evolved from that of metallic Cr to Cr nitride; at highest doses, the Fe MVV lineshape could be identified as Fe nitride. Auger and XPS spectra of implanted 304 and thermally nitrided 304 were virtually identical at comparable nitrogen concentrations. The Cr(2p3/2) binding energies of both, however, were about 1 eV lower than found in Cr nitride but 0.5 eV higher than in metallic Cr.