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

Abstract

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 ΔH_mix-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 (σ_y = 796 MPa, ε_ΤΕ = 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.