  With huge design spaces for unique chemical and mechanical properties, we
remove a roadblock to computational design of {high-entropy alloys} using a
metaheuristic hybrid Cuckoo Search (CS) for "on-the-fly" construction of
Super-Cell Random APproximates (SCRAPs) having targeted atomic site and pair
probabilities on arbitrary crystal lattices. Our hybrid-CS schema overcomes
large, discrete combinatorial optimization by ultrafast global solutions that
scale linearly in system size and strongly in parallel, e.g. a 4-element,
128-atom model [a $10^{73+}$ space] is found in seconds -- a reduction of
13,000+ over current strategies. With model-generation eliminated as a
bottleneck, computational alloy design can be performed that is currently
impossible or impractical. We showcase the method for real alloys with varying
short-range order. Being problem-agnostic, our hybrid-CS schema offers numerous
applications in diverse fields.
