Anomalous X-Ray Scattering and Extended X-Ray Absorption Fine Structure Study of the Local Structure of CrFeCoNiMo_x (x = 0.11, 0.18, and 0.23) High-Entropy Alloys

Anomalous x-ray scattering (AXS) and extended x-ray absorption fine structure (EXAFS) were used to determine the local structure of Mo in CrFeCoNiMo_x (x = 0.11, 0.18, and 0.23), a high-entropy alloy with a face-centered cubic (FCC) lattice. No superlattice peaks were observed down to the 10^–4 intensity level. This observation along with the nearly constant decrease of the FCC diffraction peaks above the Mo K absorption edge suggests that Mo atoms have no preferred site occupancy in the FCC lattice. Modeling of the EXAFS data suggests a local chemical order in CrFeCoNiMo_x, where in Mo-rich samples (e.g., x = 0.23), Mo atoms are preferably surrounded by lighter atoms, such as Cr.