Abstract
A Mössbauer effect study has been done for Fe-9.0 at%N austenite in order to clarify the interaction between interstitial atoms in the fcc lattice and the nitrogen atom distribution among the octahedral sites. Mössbauer spectra were decomposed into three components; one singlet γ0, and two sets of doublet γ1 and γ2, with a different quadrupole splitting, 0.39 mm/s and 0.70 mm/s, respectively. The ratio of Fe atoms among three components was determined by extrapolating the intensity of each component to zero sample thickness. It is concluded that N-Fe-N type dumb-bell configuration is preferentially formed in the Fe-N austenite as a result of both the repulsive and attractive interactions between 1st and 2nd neighboring nitrogen atoms, respectively. The critical temperature for the Fe4N type of ordering in the fcc solid solution is estimated to be about 150 K.
