Microstructure and Mechanical Properties of a New Refractory Equiatomic CrHfNbTaTi High-Entropy Alloy

A novel refractory CrHfNbTaTi high-entropy alloy, derived by replacement of Zr by Cr in HfNbTaTiZr, has been prepared by vacuum arc-melting. Its phase components, microstructure, and compressive properties at room temperature in as-cast and as-homogenized condition were investigated. The results show that the phase structure of CrHfNbTaTi changes from the single body-centered cubic (BCC) phase of HfNbTaTiZr alloy to multiple phases, composed of one face-centered cubic (FCC) and two BCC phases. Additionally, the yield strength of the alloy significantly increases from 926 MPa to 1258 MPa and 1366 MPa in the as-cast and as-homogenized state, respectively, while promising ductility of ~ 24.3% elongation is retained in the as-cast state. The morphology and composition of the network-shaped interdendritic regions are considered to be closely related to the change of the mechanical properties induced by elemental substitution and homogenization treatment.