Light-weight multi-principal element alloy Ti50V40Cr5Al5 with high strength-ductility and improved thermo-physical properties

The single-phase body-centered-cubic (BCC) multi-principal element alloys (MPEAs) have garnered attention as promising materials for extreme conditions in nuclear reactors. However, the limited ductility and high density of BCC MPEAs present challenges for practical applications. In this work, a novel light-weight single-phase BCC MPEA with high strength-ductility, Ti50V40Cr5Al5, was designed using the ΔHmix-δ, and M-VEC under the requirement of ρ < 6 g/cm3. The Ti50V40Cr5Al5 prepared by vacuum arc melting exhibits single-phase BCC microstructure and a low density of 5.09 g/cm³. Compared to conventional reduced activation ferritic/martensitic (RAFM) steels, the thermal expansion coefficient of this alloy is reduced by 0.19 × 10−5 K−1 to 0.49 × 10−5 K−1 (a decrease of 15–33 %), while its thermal conductivity increases by > 1.2 W/(m·°C) (an increase of >4 %) at 600 °C. Ti50V40Cr5Al5 exhibits high strength-ductility at room temperature (σy = 796 MPa, εΤΕ = 31 %) and achieves excellent strength-ductility synergy at 25–600 °C. Its yield strength is 125–333 MPa (an increase of 26–132 %) higher than that of conventional RAFM steels, with a 7.7–35.1 % (an increase of 33–396 %) higher total elongation. With its outstanding thermo-physical properties and excellent strength-ductility synergy, Ti50V40Cr5Al5 stands out as a promising candidate for structural materials of nuclear reactors.