Phase stability of V-Ta alloy using cluster expansion and Monte Carlo techniques

The ground states and the solid state part of the phase diagram of V-Ta alloys are examined by combining the Density Functional Theory based total energy calculations with the cluster expansion and the Monte Carlo techniques. In agreement with experiments, our cluster expansion of V-Ta alloy, based on the bcc lattice, does not find any compound ground state. Cluster expansion of V-Ta, based on C15 Laves lattice, on the other hand, clearly establishes that V2Ta is the ground state composition. Phase equilibrium computed by Monte Carlo simulations, using these cluster expansion Hamiltonians, produces phase boundaries in good agreement with CALPHAD and experimental literature.