Refractory High-Entropy Alloys (Postprint)

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 microhardness were rho = 13.75 g/cm3 and Hv = 4455 MPa for the W-Nb-Mo-Ta alloy and rho = 12.36 g/cm3 and Hv = 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. Published in Intermetallics, v18 p1758-1765, 2010. Prepared in collaboration with UES, Inc., Dayton, OH, General Dynamics, Corp., Dayton, OH and Department of Material Science and Engineering, University of Tennessee, Knoxville, TN. Sponsored in part by Air Force Office of Scientific Research contract no. FA8650-10-D-5226.