A new Al₁₄Co₂₈Cr₂₈Ni₃₀ hypoeutectic high entropy alloy with excellent tensile property

Eutectic high entropy alloys (HEAs) are attracting considerable interest because of their excellent combination of strength and plasticity. Recently, the hypoeutectic HEAs were reported to exhibit more favorable plasticity compared with the eutectic HEAs due to the reasonable phase content and morphology. In this study, a new Fe-free Al₁₄Co₂₈Cr₂₈Ni₃₀ hypoeutectic HEA was designed by setting the molar ratio of Ni/Al and enthalpy of mixing. The alloy was composed of primary phase with a face-centered-cubic (FCC) structure and eutectic microstructure with a mixture structure of FCC and ordered body-centered-cubic (B2) phases. The FCC phase existed in both the primary dendrite phase and eutectic microstructure was enriched in Co and Cr elements, whereas the B2 phase existed in eutectic microstructure was enriched in Al and Ni elements. The present Al₁₄Co₂₈Cr₂₈Ni₃₀ hypoeutectic HEA exhibited excellent tensile property with a yield strength of 510 ± 11 MPa, an ultimate strength of 1000 ± 7 MPa and a total elongation of 21.5 ± 1.3%, which was better than most of as-cast eutectic HEAs reported previously. The findings may bring a novel insight to explore HEAs with excellent combination of strength and plasticity, and promote the HEAs' industrial applications. (paper)