Unveiling microstructural origins of the balanced strength–ductility combination in eutectic high-entropy alloys at cryogenic temperatures
Yi Li, Peijian Shi, Mingyang Wang, Yinpan Yang, Yan Wang, Yiqi Li, Yuebo Wen, Weili Ren, Na Min, Yan Chen, Yifeng Guo, Zhe Shen, Tianxiang Zheng, Ningning Liang, Wenjun Lu, Peter K. Liaw, Yunbo Zhong, Yuntian Zhu
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.