Unveiling microstructural origins of the balanced strength–ductility combination in eutectic high-entropy alloys at cryogenic temperatures

Abstract

Eutectic high-entropy alloys (EHEAs) feature attractive strength–ductility balance at both ambient and cryogenic temperatures. Nevertheless, microstructural origins underpinning these balanced mechanical properties remain elusive. Here the deformation mechanisms of a recently-reported Al₁₉Co₂₀Fe₂₀Ni₄₁ EHEA were comparatively investigated at 298 and 77 K, which revealed a high frequency and density of dislocation multi-slip scenario in the soft eutectic lamellae and the corresponding compatible co-deformation in the adjacent hard lamellae that collectively endowed strong hetero-deformation-induced (HDI) hardening and excellent forest-dislocation hardening. Therefore, better ductility and tensile strength, in comparison to the other widely-studied EHEA system, could be sustained even at liquid-nitrogen temperatures.

GRAPHICAL ABSTRACT

IMPACT STATEMENT

We identify a new eutectic HEA system with superior strength–ductility combination at liquid-nitrogen temperatures, and provide critical microstructural insights and mechanisms into its enhanced cryogenic properties.

KEYWORDS:

• Eutectic high-entropy alloys
• mechanical properties
• multi-slip scenario
• compatible co-deformation
• HDI hardening

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was financially supported by National Key Research and Development Program of China [grant numbers 2018YFF0109404, 2016YFB0300401, 2016YFB0301401]; National Natural Science Foundation of China [grant numbers U1732276, U1860202] and National Natural Science Foundation of China [grant number 52004156].