Phase equilibria in Ni-TiC-MeC (Me: Zr, Hf, Nb, Ta) system alloys

Phase equilibria in heat resisting Ni-TiC-MeC(MeZr, Hf, Nb, Ta) system alloys were investigated. Metalographic analysis was used to study cast and annealed alloys. Phase equilibria diagram of Ni-TiC-ZrC system posesses one ternary eutectic melting at the temperature of 1175+-15 deg C and containing 6+-0.7 mol.% TiC and 4+-0.7 mol % ZrC. Two carbide phases are formed in this system alloys which composition corresponds to the position of solid solution binodal decomposition curve in quasibinary TiC-ZrC system. The state diagram of Ni-TiC-HfC system is similar to the one of Ni-TiC-ZrC system. Cast alloys of this system show a tendency to crystallizationin metastable state when carbide phase doesn't decompose into two solid solutions. In Ni-TiC-TaC system alloys carbide phase doesn't decompose even during annealing (1000 deg C, 10 hours). State diagrams of these systems possess one monovariant eutectic. When obtaining carbide phases using metallic bath the most reliable results are received when alloys with eutectic compositions are used