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