Refractory high-entropy alloys

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) angstrom for the quaternary alloy and a = 3.1832(2) angstrom for the quinternary alloy were determined with high-energy X-ray diffraction using a scattering vector length range from 0.7 to 20 angstrom(-1). The alloy density and Vickers microhardness were rho = 13.75 g/cm(3) and H-v = 4455 MPa for the W-Nb-Mo-Ta alloy and rho = 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-solution-like strengthening mechanism. (C) 2010 Elsevier Ltd. All rights reserved.