Understanding the yield strength difference in dual-phase eutectic high-entropy alloys
Zhouzhu Mao, Xi Jin, Zan Xue, Min Zhang, Junwei Qiao
Abstract
Face-centered cubic (FCC)/ordered body-centered cubic (B2)-structured Al–Co–Cr–Fe–Ni system eutectic high-entropy alloys (EHEAs) have a favorable combination of high strength and ductility in the as-cast state. However, the mechanical properties of this type of alloy vary significantly with composition. In this study, we attempted to determine the yield strength differences in FCC/B2 EHEAs. Based on reported Al 0.8 CrFeNi 2.2 , we successfully prepared three low-cost Co-free EHEAs: Al 0.82 Cr 0.8 Fe 1.2 Ni 2.18 , Al 0.83 Cr 0.6 Fe 1.4 Ni 2.17 , and Al 0.85 Cr 0.4 Fe 1.6 Ni 2.15 . All the EHEAs are shown to exhibit the same phase constituent (FCC/B2) and complete eutectic microstructure, with similar lamellar thickness but different tensile properties . We constructed a theoretical calculation model based on the Hall-Petch regime which fits the measured yield strength σ 0.2 . The yield differences for current FCC/B2 EHEAs results mainly from different intrinsic strengths of their soft FCC phases.