Abstract: Refractory high-entropy alloys (RHEAs) exhibit remarkable strengths at elevated temperatures and are hence extremely promising candidates for high-temperature structural materials. However, the RHEAs with ordered superlattice structures generally suffer from poor room-temperature plasticity, which severely hampers their widespread applications. Here, we discovered that the introduction of multicomponent ceramic nanoparticles (MCNPs) into the RHEAs makes the problem alleviative and realizes a multifold increase in plasticity without sacrificing strength. The detailed characterizations show that the improvement originates from the chemical ordering-disordering transition near MCNPs in the B2-ordered RHEAs. This transition promotes the formation of local disordered regions where the mobility of dislocations is significantly enhanced. These regions wrap around MCNPs to form a unique heterogeneous structure, which suppresses the premature microcracks by the boosted dislocation mobility. Simultaneously, the existence of stable MCNPs prevents grain coarsening at elevated temperatures by Zener pinning. These novel alloy-design ideas shed new insights into developing RHEAs with an outstanding combination of strength and plasticity.

Key words: Refractory high-entropy superalloys, Plasticity, Multicomponent ceramic nanoparticles, Ordering-disordering transition