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A dual-scale chemical fluctuation nanostructure enables CoCrFeNiPd high entropy alloy with exceptional mechanical properties at ultralow temperatures
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DOI：10.1016/j.actamat.2026.122635.png)
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Abstract
En 中文
High-entropy alloys (HEAs) have emerged as promising structural materials that exhibit remarkable improvements in strength, plasticity, and fracture toughness at extremely low temperatures. In this study, a dual-scale chemical fluctuation nanostructure was constructed in a CoCrFeNiPd HEA, which exhibits remarkable mechanical performance at ultralow temperatures. The dual-scale nanostructure consists of 10 nm-level large chemical fluctuations (L-CF) and 2-3 nm small chemical fluctuations (S-CF), as characterized by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and 3D atom probe tomography (APT). The nanostructure endows the alloy with a yield strength of 943 MPa, an ultimate tensile strength of 2240 MPa, and a fracture elongation of 55% at 15 K. Notably, the alloy maintains stable plastic flow without pernicious serrated deformation that is prevalent in other HEAs at low temperatures. In-situ neutron diffraction and TEM results show that ultralow temperatures stabilize the chemical fluctuation nanostructure, promote dislocation multiplication, and enable the synergistic operation of multiple deformation mechanisms, thereby avoiding avalanche-like dislocation motion and achieving the simultaneous enhancement of strength and ductility. This work provides a promising paradigm for designing high-performance alloys for ultralow-temperature applications by constructing multiscale chemical fluctuation nanostructures.
Keywords:
High entropy alloy
Chemical fluctuation
In situ neutron diffraction
Ultralow temperature
Plastic deformation
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9.3
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2.0W
Citations:
12.9W
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