Microstructures and room temperature mechanical properties of novel refractory high-entropy eutectic composites

This study successfully fabricated refractory high-entropy composites (RHECs) with fully eutectic structures, (WTaNbMo)C and (WTaNb)C, employing a pseudo-binary eutectic design methodology combined with thermodynamic calculations and experimental validation. The resulting ingots exhibited exceptional density, defect-free microstructures, and superior castability. The (WTaNbMo)C alloy comprises a eutectic structure with coarse BCC phases interwoven with fine BCC/MC lamellae, achieving a yield strength of 2270 MPa. In contrast, the (WTaNb)C alloy features alternating BCC/M₂C lamellar eutectic structures, demonstrating a higher yield strength of 2528 MPa. The enhanced mechanical performance arises from the BCC/M₂C eutectic with the high density of heterogeneous phase interfaces, which simultaneously improves castability and mechanical strength. These advancements highlight the potential of such alloys in promoting the practical application of refractory high-entropy alloys under extreme service conditions.