FCC γ-鉄中における窒素原子間の相互作用と原子配列

抄録

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.