Two novel Zr-rich refractory high-entropy alloys with excellent tensile mechanical properties

Refractory high entropy alloys (RHEAs), mainly consisting of high-melting-point alloying elements such as Zr, Ti, Nb, Ta and V, are promising candidates in the field of nuclear engineering. However, the poor room-temperature mechanical properties of the REHAs limit their engineering applications. In this study, Zr35Ti30Nb20Al10Ta5 and Zr35Ti30Nb20Al10V5 RHEAs were developed. Ductile body-centered-cubic (BCC) matrixes were obtained by regulating the valence electron concentration (VEC). The introduction of Al elements promoted the formation of fine and dispersedly distributed B2 nanoprecipitates in the BCC matrix to enhance the strength. At room temperature, the cast Zr35Ti30Nb20Al10Ta5 and Zr35Ti30Nb20Al10V5 alloys possess tensile yield strengths of ∼850 MPa/848 MPa with elongations of ∼25%/16%. The high yield strength is mainly contributed by solid solution strengthening and nanoprecipitate strengthening.