Abstract
The impacts of local chemical order (LCO) on the physical properties of high-entropy alloys (HEAs) have been widely discussed. However, the difficulty in unambiguously observing LCO with high precision poses a great challenge in establishing microscopic mechanisms regarding the impacts of LCO on physical properties. Furthermore, it is still unclear whether the LCO extends to HEA surfaces, which may impact surface-based properties, such as corrosion, oxidation, and catalytic activities. Through the utilization of scanning tunneling microscopy (STM), two surface LCO domains with corresponding \(\sqrt{5}\times \sqrt{5}R\pm 26.6^\circ\) quasi-long-range orderings (QLRO) are directly observed on a CoCrFeMnNi surface. Density functional theory (DFT) calculations identify the LCO within QLRO supercells. The findings provide evidence of the existence of the surface LCO and demonstrate a method to directly observe the surface LCO of HEAs. With the ability to unambiguously resolve elemental configuration at atomic scale, the understanding of how LCO influences surface-based properties can be achieved, facilitating the design of HEAs with tailored functionalities.
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Data availability
Data is available upon request. The LEED, STM, and DFT calculated PDOS datasets generated during and analyzed during the current study are available in the figshare repository62.
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Acknowledgements
The sample fabrication, characterization, STM measurements and analysis, and DFT calculations are supported by National Science Foundation DMR-2219416 (T.Y.C. and G.B.), and CMMI-2436601 (G.B.). Insightful discussion on the short-range order is supported by DMR-1611180 (P.K.L.), DMR-1809640 (P.K.L.), DMR-2226508 (P.K.L.), and Air Force Office of Scientific Research AF AFOSR-FA9550-23-1-0503 (P.K.L). C.-W.T. and J.-W.Y. thank financial support from the High Entropy Materials Center as part of the Featured Areas Research Center Program, within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) and also from Project National Science and Technology Council (NSTC) 113-2221-E-007-036 (C.W.T. and J.W.Y.) and 112-2221-E-007-032 (C.W.T. and J.W.Y.) of the National Science and Technology Council (NSTC) in Taiwan. EWH thanks the support of the NSTC under Grants NSTC 113-2811-E-A49-525 (E.W.H.), 113-2221-E-A49-003 (E.W.H.), and 114-2923-E-A49-003-MY3 (E.W.H.).
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T.Y.C. conceived and designed the experiments, analysis, and interpretation of the data. L.K. performed measurements and analyzed experimental data. P.S. and G.B. prepared the HEA sample. P.S. performed DFT calculations. C.-W.T., E.-W.H., P.K.L., and J.-W.Y. contributed intellectually to the short-range order discussions. All authors discussed the results and commented on the manuscript.
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Kim, L., Sharma, P., Tsai, CW. et al. Direct visualization of the existence of surface local chemical order in a high-entropy CoCrFeMnNi alloy. Nat Commun (2026). https://doi.org/10.1038/s41467-026-71170-z
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DOI: https://doi.org/10.1038/s41467-026-71170-z
