Abstract:The microstructural evolution, phase stability, and mechanical properties of Al-Li-Mg-Ti-M (M=Zn, Zr, V) lightweight high-entropy alloys (LW-HEAs) were investigated. The LW-HEAs with three components, Al₂₀Li₂₀Mg₁₀- Ti₄₀Zn₁₀ (#Zn), Al₂₀Li₂₀Mg₁₀Ti₃₀Zr₂₀ (#Zr), and Al₂₀Li₂₀Mg₁₀Ti₃₀V₂₀ (#V), were designed according to the thermo- dynamic design criteria of HEA, and prepared via a combination process of mechanical alloying and cold-press sintering. The effects of alloy composition and sintering temperature on the microstructure and mechanical properties of the LW-HEAs were studied. The results show that the as-milled Al-Li-Mg-Ti-M (M=Zn, Zr, V) LW-HEAs form a simple structure with HCP-type solid solution as the primary phase, a dual-HCP type solid solution phase, and a BCC phase, respectively. After cold-press sintering, the #Zn and #V alloys undergo obvious phase transformation; while the #Zr alloy with dual-HCP phases exhibits the best phase stability during heat treatment. The #V-750 °C alloy demonstrates the maximum hardness and specific strength of HV 595.2 and 625 MPa？cm³/g, respectively, under the combined effect of solid solution strengthening of BCC phase and precipitation strengthening of β-AlTi₃. Moreover, the #Zr-650 °C, #Zr-750 °C, and #Zn-650 °C alloys are expected to have excellent plasticity.

Key words: lightweight high-entropy alloy; mechanical alloying; microstructural evolution; phase stability; specific strength; plasticity