Materials with excellent high-temperature strength are now sought for applications in hypersonics, fusion reactors, and aerospace technologies. Conventional alloys and eutectic multiprincipal-element alloys (MPEAs) exhibit insufficient strengths at high temperatures due to low melting points and microstructural instabilities. Here, we report a strategy to achieve exceptional high-temperature microstructural stability and strength by introducing eutectic carbide in a refractory MPEA. The synergistic strengthening effects from the multiprincipal-element mixing and strong dislocation blocking at the interwoven metal-carbide interface make the eutectic MPEA not only have outstanding high-temperature strength (>2 GPa at 1473 K) but also alleviate the room-temperature brittleness through microcrack tip blunting by layered metallic phase. This strategy offers a paradigm for the design of the next-generation high-temperature materials to bypass the low–melting point limitation of eutectic alloys and diffusion-dominated softening in conventional superalloys.

We developed a eutectic high-entropy alloy (EHEA) with appreciable high-temperature strength-plasticity balance. Structural characterizations of the as-cast sample revealed a lamellar structure with austenite (face-centered-cubic, FCC) and Laves phases. Upon annealing at 873 K, precipitation of nanoscale (Ni, Al, and Zr)-rich L1₂ phase from the FCC phase took place, which eventually transformed into a martensitic (hexagonal, ε) phase with rearrangement of atomic species. Compressive properties revealed a brittle behavior at temperatures below 873 K, but changed to a ductile behavior with considerable strain hardening at 973 K, due to the formation of a high density of deformation twins observed by transmission electron microscopy. GRAPHICAL ABSTRACT IMPACT STATEMENT A eutectic high-entropy alloy with attractive high-temperature compressive strength-plasticity balance was realized by tuning the microstructure via heat treatment, during which nanoscale L1₂ phase formed within the FCC matrix phase.

Nb alloys with high strength and relatively low density are sought for high-temperature applications. However, due to strain softening, conventional Nb alloys often exhibit insufficient high-temperature strengths. Here we report a strategy to design a novel lightweight and thermally-stable Nb alloy by combining the notion of eutectics and refractory carbide. The resulting Nb₂MoWC_0.96 eutectic alloy exhibits a high-temperature specific compressive strength of 77.2 MPa/·cm³·g¹ at 1673 K with a retained engineering plasticity of 37.5%, both are notably higher than the existing Nb and Nb-containing alloys. This work demonstrates that both the strength and plasticity of Nb alloys can be further optimized with refractory carbide and eutectics. GRAPHICAL ABSTRACT IMPACT STATEMENT Combining the notion of eutectics with refractory carbide makes high strength, large plasticity Nb alloy with good microstructural stability.