Critical assessment and experimental investigation of Co-Ni-Ti phase equilibria

Literature data about phase equilibria and thermodynamics of the Co-Ni, Co-Ti, Ni-Ti and Co-Ni-Ti systems have been reviewed and critically assessed. Co-Ni-Ti phase equilibria are not completely known and contradictory results have been reported, especially about existence, stability range and phase relations of the Ti(Co,Ni)3 ternary phase in the region at x(Ti)<0.5. Then the 900 °C isothermal section in the mentioned composition range has been experimentally investigated by means of optical and electron microscopy, electron probe micro-analysis and powder X-ray diffraction. Moreover the existence of the Ti(Co,Ni)3 phase has been confirmed and its stability checked, at least down to 500 °C.