  High entropy alloys (HEAs) are multicomponent compounds whose high
configurational entropy allows them to solidify into a single phase, with a
simple crystal lattice structure. Some HEA's exhibit desirable properties, such
as high specific strength, ductility, and corrosion resistance, while
challenging the scientist to make confident predictions in the face of multiple
competing phases. We demonstrate phase stability in the multicomponent alloy
system of Cr-Mo-Nb-V, for which some of its binary subsystems are subject to
phase separation and complex intermetallic-phase formation. Our
first-principles calculation of free energy predicts that the configurational
entropy stabilizes a single body-centered cubic (BCC) phase from T = 1,700K up
to melting, while precipitation of a complex intermetallic is favored at lower
temperatures. We form the compound experimentally and confirm that it forms as
a single BCC phase from the melt, but that it transforms reversibly at lower
temperatures.
