Microstructures and mechanical properties of novel MoTaVW refractory high-entropy alloys

Abstract

Refractory high-entropy alloys (RHEAs) containing multiple principal alloying elements have created a growing interest in exploring superalloys applications due to their high melting points and excellent softening resistance. The room-temperature brittleness and oxygen sensitivity greatly restrict their further processing and application. Here, utilizing the unique high strength of Vanadium (V) among alloy elements and cocktail effect of HEAs, we designed a MoTaVW RHEAs with equal atomic ratio, that exhibit multiphase phases (Ta-rich, Mo-rich and V-rich phase) with different composition at different sintering temperatures and the alloy elements in BCC solid solution tend to be uniformly distributed as the increased sintering temperature. Exploring the room-temperature compressive properties and underlying deformation mechanisms, the MoTaVW RHEAs exhibit the yield strength (σy) of 1420 MPa and the plastic strain (εp) of 18 %, that achieved good combination of strength and plasticity compared with other most known BCC RHEAs, which are attributed to high solid solution strengthening caused by lattice distortion and the cross slip of screw dislocations on the close-packed plane that can enhance the synergistic effect of strength and plasticity. These results reveal the MoTaVW RHEAs is a very promising materials for compositional space in RHEAs.