The microstructure and mechanical properties of a novel refractory AlNbTiZr high-entropy alloy (HEA) with a low density of ∼5.85 g cm−3 were investigated after arc melting and homogenisation at 1473 K for 5 h. The as-cast HEA exhibits a single-phase ordered body-centred cubic (B2) structure. A hexagonal Zr5Al3-type second phase is introduced into the HEA through homogenisation treatment, resulting in increase of the yield strength, ultimate compressive strength and fracture strain by 70 MPa, 308 MPa and 9.2%, respectively. These results indicate that the introduction of the hexagonal Zr5Al3-type second phase into the B2 matrix can simultaneously improve the HEA strength and ductility, showing a strength–ductility combination superior to those of most reported refractory HEAs.
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