The Atomic Site Occupancies in the Fe-Cr σ-Phase
The atomic site distribution of the complex σ-phase structure (P42/mnm) has been studied using density functional theory (within the EMTO and WIEN2k codes) applying the cluster expansion method in a mean field approximation at finite temperatures. We found that at low temperatures Fe atoms predominantly occupy the icosahedrally coordinated (A,D) sites, Cr atoms prefer the (B,E) sites with the high coordination numbers, while the C site remains mixed. However, at higher temperature close to 1000 K all occupations become more and more mixed and reproduce well the available experimental data.
J.-L. Bobet, B. Chevalier and D. Fruchart
E. Kabliman et al., "The Atomic Site Occupancies in the Fe-Cr σ-Phase", Solid State Phenomena, Vol. 170, pp. 13-16, 2011