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.