A family of high entropy alloys rich in Al have been produced by arc-melting and their microstructures, predicted by thermodynamic modeling and observed experimentally, are reported along with the alloys’ density and Vickers microhardness. Alloy 1 ( \(\text{Al}_{2.7}\) CrFeMnV) consisted of a polycrystalline single-phase BCC microstructure with relatively equiaxed grains. Alloy 2 ( \(\text{Al}_{2.7}\) CrFeTiV) consisted of a polycrystalline BCC matrix containing G phase precipitates with complex dendritic shapes and a Laves phase with large aspect ratio lamellae. Alloy 3 ( \(\text{Al}_{2.7}\) CrMnTiV) consisted of a BCC matrix containing lath-shaped AlTi \(\text{L1}_0\) precipitates and regions with coherent cuboidal precipitates having an ordered BCC structure. This ordered BCC phase was not predicted by equilibrium thermodynamic calculations but a B2 phase was expected using a metastable prediction. The regions of Alloy 3 containing the ordered BCC cuboids showed evidence of enhanced Vickers microhardness. The alloys were characterized in the as-cast state by several techniques, including scanning and transmission electron microscopy, X-ray diffraction, atom-probe tomography, and electron backscatter diffraction, and these results were used to validate the thermodynamic predictions by Thermo-Calc.
