Temperature dependence of the short-range order parameter for Fe_0.90Cr_0.10 and Fe_0.88Cr_0.12 alloys

The ⁵⁷Fe Mössbauer spectra for the iron-based solid solutions Fe_0.90Cr_0.10 and Fe_0.88Cr_0.12 were measured at different temperatures ranging from 300 K to 900 K. Analysis of the obtained spectra shows that the distribution of impurity atoms in the two first coordination shells of ⁵⁷Fe nuclei is not random and it cannot be described by the binomial distribution. Quantitatively, the effects were described in terms of the atomic short-range order (SRO) parameters and the pair-wise interaction energy with the help of a quasi-chemical type formulation introduced by Cohen and Fine. The obtained results reveal strong clustering-type correlations in the studied samples (a predominance of Fe-Fe and Cr-Cr bonds). Moreover, the changes in SRO values observed during thermal processing suggest that the distribution of Cr atoms in an α-iron matrix is strongly temperature dependent.