Datei im Netzwerk der BAM verfügbar ("Closed Access")
Filtern
Dokumenttyp
- Zeitschriftenartikel (1)
- Vortrag (1)
Sprache
- Englisch (2)
Schlagworte
Organisationseinheit der BAM
- 6 Materialchemie (2)
- 6.3 Strukturanalytik (2)
Eingeladener Vortrag
- nein (1)
The superior properties of high-entropy multi-functional materials are strongly connected with their atomic heterogeneity through many different local atomic interactions. The detailed element-specific studies on a local scale can provide insight into the primary arrangements of atoms in multicomponent systems and benefit to unravel the role of individual components in certain macroscopic properties of complex compounds. Herein, multi-edge X-ray absorption spectroscopy combined with reverse Monte Carlo simulations was used to explore a homogeneity of the local crystallographic ordering and specific structure relaxations of each constituent in the equiatomic single-phase facecentered cubic CrMnFeCoNi high-entropy alloy at room temperature. Within the considered fitting approach, all five elements of the alloy were found to be distributed at the nodes of the fcc lattice without any signatures of the additional phases at the atomic scale and exhibit very close statistically averaged interatomic distances (2.54 – 2.55 Å) with their nearest-neighbors. Enlarged structural displacements were found solely for Cr atoms. The macroscopic magnetic properties probed by conventional magnetometry demonstrate no opening of the hysteresis loops at 5 K and illustrate a complex character of the long-range magnetic order after field-assisted cooling in ± 5 T. The observed magnetic behavior is assigned to effects related to structural relaxations of Cr. Besides, the advantages and limitations of the reverse Monte Carlo approach to studies of multicomponent systems like high-entropy alloys are highlighted.
Extended X-Ray absorption fine structure (exafs) to study local constitution of high-entropy alloys
(2021)
Modern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties. Herein, peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic (fcc)- and body-centered cubic (bcc)-structured high-entropy Alx-CrFeCoNi alloys (x = 0.3 and 3, respectively) are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges. Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision.