  The vastness of the space of possible multicomponent metal alloys is hoped to
provide improved structural materials but also challenges traditional,
low-throughput materials design efforts. Computational screening could narrow
this search space if models for materials stability and desired properties
exist that are sufficiently inexpensive and accurate to efficiently guide
experiments. Towards this effort, here we develop a method to rapidly assess
the thermodynamic stability of a metal alloy composition of arbitrary number of
elements, stoichiometry, and temperature based on density functional theory
(DFT) data. In our model, the Gibbs free energy of the solid solution contains
binary enthalpy contributions and ideal configurational entropy, whereas only
enthalpy is considered for intermetallic competing phases. Compared to a past
model for predicting the formation of single-phase high-entropy alloys [Phys.
Rev. X 5, 011041 (2015)], our method is similarly inexpensive, since it
assesses enthalpies based on existing DFT data, but less heuristic, more
broadly applicable, and more accurate (70--75%) compared to experiment.
