Data-driven electron-diffraction approach reveals local short-range ordering in CrCoNi with ordering effects.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36333312.
- Also identified by DOI 10.1038/s41467-022-34335-0 and PMC identifier 9636235.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The exceptional mechanical strength of medium/high-entropy alloys has been attributed to hardening in random solid solutions. Here, we evidence non-random chemical mixing in a CrCoNi alloy, resulting from short-range ordering. A data-mining approach of electron nanodiffraction enabled the study, which is assisted by neutron scattering, atom probe tomography, and diffraction simulation using first-principles theory models. Two samples, one homogenized and one heat-treated, are observed. In both samples, results reveal two types of short-range-order inside nanoclusters that minimize the Cr-Cr nearest neighbors (L1<sub>2</sub>) or segregate Cr on alternating close-packed planes (L1<sub>1</sub>). The L1<sub>1</sub> is predominant in the homogenized sample, while the L1<sub>2</sub> formation is promoted by heat-treatment, with the latter being accompanied by a dramatic change in dislocation-slip behavior. These findings uncover short-range order and the resulted chemical heterogeneities behind the mechanical strength in CrCoNi, providing general opportunities for atomistic-structure study in concentrated alloys for the design of strong and ductile materials.