A Low-Cost, Strong, and Ductile Single-Phase Nb-Based Refractory Complex Concentrated Alloy

The development of structural materials capable of sustained operation above 1200 °C is critical for next-generation energy and aerospace systems; however, Ni-based superalloys are fundamentally constrained by their melting temperatures, while conventional Nb-based refractory alloys are limited by modest specific strength and high cost. Here, we report on the design and mechanical performance of a cost-effective, non-equiatomic refractory complex concentrated alloy (RCCA), Nb45Ta15Ti20V20, engineered to overcome these limitations. Specifically, its specific strength surpasses wrought C-103 and rivals additively manufactured (AM) C-103 at temperatures up to 1300 °C while maintaining extensive room temperature tensile ductility (>10 %). Coupled with a high melting point (~2167 °C), reduced density (8.67 g/cc), and a raw material cost of ~$130/kg compared to >$500/kg for wrought C-103 and >$2,500/kg for AM C-103, this alloy delivers superior specific strength-cost efficiency, highlighting the promise of non-equiatomic RCCAs as viable alternatives to commercial refractory alloys.