Effect of Solid Solution Treatment on the Microstructure and Properties of AlNb_1.5TaTi₂Zr_1.5 Refractory High-Entropy Alloy

The refractory high-entropy alloy of AlNb_1.5TaTi₂Zr_1.5 was prepared by vacuum arc melting, and the alloy was subjected to solid solution treatment at 1473 K/2 h under an argon environment. The microstructures and mechanical properties of AlNb_1.5TaTi₂Zr_1.5 in both the as-cast and solid solution states were studied. The results showed that the density of the as-cast AlNb_1.5TaTi₂Zr_1.5 alloy is 6.85 g/cm³, and it has a two-phase structure consisting of a BCC matrix and a second phase of HCP. After solid solution treatment, the phase composition of the BCC microstructure was accompanied by the precipitation of a B2-ordered phase. Due to the dual effect of lattice distortion and the obstruction of B2-ordered particles, the hardness of the solid solution state AlNb_1.5TaTi₂Zr_1.5 alloy reached a high value of 7.42 GPa. The compressive stress at room temperature was 2370.05 MPa, and the high-temperature compressive stress in solid solution at 873 K was 1061.68 MPa. The compressive properties at room and high temperatures were greatly improved, and their properties were higher than those of the as-cast state.