  The ability to predict the composition- and temperature-dependent stability
of refractory complex concentrated alloys (RCCAs) is vital to the design of
high-temperature structural alloys. Here, we present a model based on
first-principles calculations to predict the thermodynamic stability of
multicomponent equimolar solid solutions in a high-throughput manner and apply
it to screen over 20,000 compositions. We develop a database that contains
pairwise mixing enthalpy of 17 refractory metals using density-functional
theory (DFT)-based total energy calculations. To these, we fit thermodynamic
solution models that can accurately capture the mixing enthalpy of
multicomponent BCC solid solutions. By comparing their energy with
DFT-calculated enthalpy of intermetallics from the Materials Project database
and using convex hull analyses, we identify the stable phase of any RCCA as a
function of temperature. The predicted stability of NbTiZr, NbTiZrV, and
NbTiZrVM (M = Mo,Ta,Cr) systems as a function of temperature agree well with
prior experimental observations. We apply our model to predict the phase
evolution in NbVZr-Tix (0 < x < 1), which is confirmed experimentally using a
high-throughput, laser deposition-based synthesis technique. This method
provides a fast and accurate way to estimate the phase stability of new RCCAs
to expedite their experimental discovery.
