Hexagonal High-entropy Alloys

We report on the discovery of a high-entropy alloy (HEA) with a hexagonal crystal structure. Equiatomic samples in the alloy system Ho-Dy-Y-Gd-Tb were found to solidify as homogeneous single-phase HEAs. The results of our electron diffraction investigations and high-resolution scanning transmission electron microscopy are consistent with an Mg-type hexagonal structure. The possibility of hexagonal high-entropy alloys in other alloy systems is discussed.