Refractory high-entropy alloys

摘要

Two refractory high-entropy alloys with near-equiatomic concentrations, W-Nb-Mo-Ta and W-Nb-Mo-Ta-V, were produced by vacuum arc melting. Despite containing many constituents both alloys have a single-phase body-centered cubic (BCC) structure. The lattice parameters a = 3.2134(3) A for the quaternary alloy and a= 3.1832(2) A for the quinternary alloy were determined with high-energy X-ray diffraction using a scattering vector length range from 0.7 to 20 A~(-1). The alloy density and Vickers micro-hardness were ρ=13.75 g/cm~3 and H_v= 4455 MPa for the W-Nb-Mo—Ta alloy and ρ =12.36 g/cm~3 and H_v= 5250 MPa for the W-Nb-Mo-Ta-V alloy. The exceptional microhardness in these alloys is greater than any individual constituent, suggesting the operation of a solid-solutionlike strengthening mechanism.