Short-Range Order in Fe-Rich Fe-Cr Alloys as Revealed by M\"ossbauer Spectroscopy

TL;DR

This study uses Mössbauer spectroscopy to analyze the short-range atomic order of Cr in Fe-Cr alloys, revealing configuration-dependent clustering and an inversion of order at specific compositions, providing more detailed insights than previous research.

Contribution

It provides a detailed analysis of atomic configurations in Fe-Cr alloys, showing configuration-specific short-range order and clarifying the inversion point of the order parameter.

Findings

Cr atoms in 2NN are randomly distributed

Clustering occurs with Cr in 1NN or both shells

Inversion of the order parameter occurs only with one Cr in 1NN

Abstract

Distribution of Cr atoms in Fe_{100-x}Cr_x alloys with x \le 25 within the first two coordination shells, 1NN-2NN, around probe 57Fe atoms was studied by means of the M\"ossbauer Spectroscopy. Clear evidence was found that the distribution is characteristic of a given atomic configuration. Only the configurations with Cr atoms situated in 2NN exhibit a quiasi-random distribution, while those with Cr atoms present in 1NN shell and those with Cr atoms in both shells is evidently not random showing clastering or anticlastering features. These findings are novel and much more complete than the up-to-date knowledge according to which there is an inversion of the short-range order parameter at x = 11. The inversion in the present study was found only for the configuration with one Cr atom in 1NN. On average, Cr atoms are distributed almost randomly within the 1NN-2NN volume for x \eq ~10, and do cluster for larger x.