Mössbauer Effect in Iron-Nitrogen Alloys and Compounds

Abstract

Mössbauer effects of ⁵⁷Fe in iron-nitrogen martensite and its tempering stages were measured. The spectra were resolved into the components corresponding to the 1st, 2nd, 3rd, 4th and farther nn Fe for each interstitial nitrogen atom. The analysis showed the localized perturbations by the nitrogen atoms on a host iron lattice similar to the case of iron-carbon martensite. The principal axis of electric field gradient at the 2nd nn Fe in the α″-Fe₁₆N₂ were determined to be directed to the nitrogen atom, not being parallel to the c-axis. The number of s and d electrons for the 1st nn Fe in some iron-nitrogen compounds were determined. The reduction of internal field, larger for interstitial alloys and compounds relative to substitutional ones, was proportional to the coordination number, n, to the neighboring nonmetal atoms. While, the variation of isomer shift depended upon both n and nonmetal concentration c.