Eutectic high-entropy alloys (EHEAs) can achieve a balance of high strength and ductility. It has been found that the mechanical properties of hypoeutectic high-entropy alloys are superior to those of EHEAs. In this work, hypereutectic Al_1.1CoCrFeNi_2.1 alloy was prepared, and the mechanical properties in a wide temperature range were studied. The presence of both soft ordered L1₂ and hard BCC (B₂) phases results in a combination of ductile and brittle fracture modes. The Al_1.1CoCrFeNi_2.1 hypereutectic high-entropy alloy contains more primary soft L1₂ phases, which ensure excellent ductility. Moreover, the Orowan by-passing mechanism caused by the B₂ precipitates increases in the strength of the alloy for low-temperature tensile tests (−100 °C and 23 ± 2 °C). The −100 °C test exhibits a dimple morphology and demonstrates the highest ultimate tensile strength of 1231 MPa, along with an excellent elongation of 44%. At high tensile temperatures (650 °C, 750 °C, and 850 °C), the dislocation cutting mechanism and dynamic recrystallization increase the plasticity. However, the presence of a large number of cracks near the spherical primary L1₂ phase significantly reduces the ductility and strength. The results show that the hypereutectic Al_1.1CoCrFeNi_2.1 exhibits superior plasticity and strength properties at low temperatures. The findings of the article provide a new approach to enhancing the comprehensive mechanical properties of hypereutectic alloys.

Refractory high-entropy alloys (RHEAs) have drawn much attention in the field of materials science for their unique properties and wide compositional design space. The Nb₃₅Zr₂₆Ti₁₉Hf₁₅Mo₅ alloy is important for exploring RHEAs’ potential in high-temperature applications. It can break through existing material limitations and bring benefits to related fields, especially in the aerospace field. This paper focuses on Nb₃₅Zr₂₆Ti₁₉Hf₁₅Mo₅ RHEAs and studies the effects of cold rolling and heat treatment on its microstructure and mechanical properties. The alloy has a single-phase BCC structure. As rolling reduction rises from 20% to 80%, the alloy’s strength increases notably while plasticity drops. At 80% rolling reduction, the tensile strength reaches 1408 MPa, and the elongation is 10.5%. During rolling, grains deform along the rolling direction, the number of low-angle grain boundaries grows, and dislocation and solid solution strengthening effects are enhanced. With the increase in annealing temperature, recrystallized grains increase, and the change in grain-boundary structure weakens the strengthening effect, leading to a strength decrease and a plasticity increase. After annealing at 800 °C, the elongation reaches 17%, and the dislocation density in the alloy decreases with a recrystallization degree of 49%.