Phase Equilibria in the Al-Co-Ni Alloy System

The phase equilibria in the Ni-Co rich region (<50 at.%Al) of the Al-Co-Ni system were studied experimentally for two isothermal sections at 1100 and 800 °C. Metallography, energy dispersive spectroscopy, hardness and x-ray diffraction were used for characterization and determination of γ, γ′ and β phases within the ternary system. Phase boundaries in the isothermal sections and a partial liquidus projection are modified compared to previously published work. Comparison is made to the isothermal sections computed using Thermo-Calc and the TCNI8 database. No definitive experimental evidence corroborating the predicted existence of a Nishizawa horn was obtained.