Experimental investigations of the Co–Ni–Ti system: Liquidus surface projection and isothermal section at 1373 K

Abstract

The liquidus surface projection and isothermal section at 1373 K of the Co–Ni–Ti system have been established by using the methods of scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (PXRD), and differential thermal analysis (DTA). 9 primary solidification regions and 6 ternary invariant reactions were deduced in the liquidus surface projection. 7 three-phase regions and 16 two-phase regions were derived in the isothermal section at 1373 K. Besides, the PXRD results indicated that the ternary compound τ with Co3V-structure existed in both liquidus surface projection and isothermal section at 1373 K. The ternary compound τ formed the extended primary field in the centre of the liquidus surface projection and its homogeneity ranges of Co in the isothermal section were measured to be from 34 to 51 at%. The present experimental results could be used as guidance to practical applications and input to future thermodynamic assessments.