A first-principles study of the stability and mechanical properties of ternary transition metal carbide alloys

摘要: First-principles calculations were carried out to investigate electronic structure, phase stability, elastic properties, Debye temperature, and hardness of the TiC–HfC TiC–TaC random solid solutions as functions composition. For TiC–HfC, significant miscibility gaps with consolute temperatures about 1975 K are revealed in binodal spinodal curves. The negative deviation moduli from linearity obtained for whereas, TiC–TaC, these characteristics above their linear interpolation between end members. Concentration dependences temperature both systems have a curvature. To clarify possible mechanism stabilization or destabilization other similar carbide systems, mixing energies M1 1 − xM2 xC alloys, where M2 transition metals IV, V, partially VI groups, calculated. It is found that behavior M1C–M2C alloys different groups depending on composition determined by difference cell volumes members, Δ V C, degree occupancy metal band, shape density states band region. Values C mainly responsible positive valence electron concentrations (VECs) equal 8 9 which weakly changes maximum VECs members predicted be reached compositions VECs = 8.5–8.75.First-principles M...