Abnormal chemical composition fluctuations in multi-principal-element alloys induced by simple cyclic deformation

High entropy alloys exhibit excellent combination of mechanical properties because of the unique composition fluctuations, termed as 'concentration wave'. The concentration wave was closely related to multiple aspects, including the fluctuation of local strain energy, local atomic environment, electronegativity, etc. Here we report for the first time that the amplitude of the concentration wave can be mechanically tailored under cyclic deformation in a well-known Cantor alloy. Atomic-scale energy-dispersive X-ray spectroscopy (EDS) mapping reveals that cyclic deformation may dynamically induce the clustering of solute atoms with a size of 1-3 nm, thus resulting in a higher concentration wave amplitude. The concentration wave promotes strong interactions between dislocations and local solute clusters. Aside from the typical Taylor strengthening contribution due to the presence of isolated dislocations, the strength enhancement from the mechanically induced composition fluctuations was quantified to be as high as similar to 70 MPa, about one-third of the yield strength of the alloy without pre-deformation. This opens up a novel strategy of designing high strength alloys by tailoring solute configurations. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

The amplitude of the concentration wave in a Cantor alloy can be mechanically tailored under cyclic deformation, resulting in an enhancement of alloy strength. Atomic-scale mapping reveals that cyclic deformation can induce the clustering of solute atoms and promote interactions between dislocations and local solute clusters.