Structures and properties of the (NbMoTaW)100−xCx high-entropy composites

•High-entropy composites (NbMoTaW)100−xCx with high strength are synthesized by vacuum arc melting.•Appropriate C addition is effective in enhancing the compressive strength and ductility.•The (NbMoTaW)100−xCx alloys are composed of high-entropy alloys and high-entropy ceramics. [Display omitted] Refractory high-entropy alloys exhibit potential applications as high-temperature structural materials. Combining the advantages of high-entropy alloys (HEAs) and high-entropy ceramics (HECs), novel high-entropy composites (NbMoTaW)100−xCx with high compressive strength were synthesized by vacuum arc melting. The effect of C addition on the microstructures and mechanical properties was investigated. Appropriate C addition was effective in enhancing the compressive strength and ductility. The NbMoTaWC alloy showed 2.5 times that of the NbMoTaW HEA in compressive strength. The NbMoTaWC alloy comprised a combination microstructure of body-centered cubic (BCC) structural HEA and face-centered cubic (FCC) structural HEC. By etching the NbMoTaWC alloy, the FCC phase was demonstrated to be HEC. The (NbMoTaW)100−xCx alloys, composed of HEA and HEC, were demonstrated to be high-entropy composites. New functionality and applicability may be discovered in this kind of high-entropy composites with non-metallic alloying elements, such as C, B, N, and Si.