Thermal Stability and Mechanical Properties of Low-Activation Single-Phase Ti-V-Ta Medium Entropy Alloys

A series of titanium-vanadium-tantalum (Ti-V-Ta) medium entropy alloys have been fabricated with all of them exhibiting a single-phase body-centered cubic structure in the homogenized states, and their thermal stability as well as their mechanical properties have been investigated. Among the four studied alloys, Ti₂₇V₃₃Ta₄₀, Ti₃₃V₃₃Ta₃₄, Ti₄₀V₃₃Ta₂₇, and Ti₄₅V₂₀Ta₃₅, the equi-atomic Ti₃₃V₃₃Ta₃₄ has shown the highest thermal stability, without secondary phases formed after annealed at 400–700°C for 48 h, while decompositions have been observed in the other three alloys. All the four alloys have exhibited a good compression strength of 394–527 MPa at 800°C, while, except Ti₂₇V₃₃Ta₄₀, maintaining an acceptable tensile ductility with fracture strains of 7.6–13% at room temperature. Furthermore, the low neutron activity of the Ti-V-Ta alloys grant them application potentials in nuclear engineering.