Lightweight, Refractory High-Entropy Alloy, CrNbTa0.25TiZr, with High Yield Strength

A new lightweight, refractory high entropy alloy (HEA), CrNbTa0.25TiZr, was prepared by arc-melting under a vacuum condition. The as-cast and annealed CrNbTa0.25TiZr possessed identical dual-phase components: a BCC + a cubic Laves phase. After annealing, the Laves phase matrix in the as-cast alloy was replaced by the BCC phase, possibly due to the diffusion of Cr, which have a much smaller atomic radius than the other principal elements. From a performance perspective, the yield strength significantly increased from 926 MPa of the as-cast HfNbTaTiZr to 1800 MPa and 1500 MPa for as-cast and annealed CrNbTa0.25TiZr, while its density (7.25 g/cm3) is only 73% of HfNbTaTiZr. The microstructure evolution of the stiff cubic Laves phase is highlighted to unveil the promising strength of the CrNbTa0.25TiZr.