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Page 12 of 15 Ying et al. Microstructures 2023;3:2023018 https://dx.doi.org/10.20517/microstructures.2022.47

characterization techniques to understand the structure and properties of these alloys. The conclusions are
summarized below:

(1) The B O fluxing treatment achieved a large degree of undercooling (385 K) of the centimeter-size N-
3
2
HEAs alloy melts.

(2) The fluxed N-HEAs had a network-like structure with a wavelength of 3-5 μm; one sub-network
consisted of a hard Cr B-type intermetallic phase, while the other was a soft FCC solid solution.
2

(3) The volume fraction of the two sub-networks could be tailored by varying the B concentration, resulting
in a gradual change in the yield strength and compressive strain of the N-HEAs. When the B content
decreased from 17% to 12%, the yield strength decreased from 1.6 to 1.1 GPa and the compressive strain
increased from 20% to 70%.

(4) N-HEAs with B contents of 12% and 15% further exhibited a good tensile ductility of 19% and 14%,
respectively. The in situ synchrotron X-ray diffraction analysis of the tensile behavior demonstrated that the
whole deformation process could be divided into three regions based on the lattice strain evolution. This
heterogeneous deformation originated from the strength difference between the two phases. Dynamic stress
partitioning between the soft FCC phase and the hard Cr B-type intermetallic phases induced a cooperative
2
deformation, which improved the ductility.

This work provides an industry-friendly route to fabricate N-HEAs with superior and controllable
mechanical properties. Moreover, microalloying and thermal/mechanical treatment could be employed to
further develop fluxed N-HEAs with excellent strength and ductility.

DECLARATIONS
Acknowledgements
We acknowledge Ms. Weixia Dong for her help in DSC measurements. This research used the resources of
the Advanced Photon Source, a US Department of Energy (DOE) Office of Science User Facility operated
for the DOE Office of Science by Argonne National Laboratory (No. DE-AC02-06CH11357). We
acknowledge the support of the GPPD beamline of China Spallation Neutron Source (CSNS) in providing
neutron diffraction research facilities.

Authors’ contributions
Design: Lan S, Wu Z
Experiments and data collection: Yang X, Tao K, Guo Z, Wang L, Fu S, Lou Y, Ren Y, He L
Data analysis: Ying H, He H, Liu S, Ge J, Zhu H
Manuscript writing: Ying H, He H, Lan S, Wu Z
Manuscript revision and supervising: Lan S, Wu Z
All authors have read and agreed to the published version of the manuscript.

Availability of data and materials
The data that support the findings of this study are available from the corresponding author upon
reasonable request.