Thermodynamic Assessments of the Ni-Cr-Ti System and Atomic Mobility of Its fcc Phase

Thermodynamic assessments have been performed for the Ni-Ti binary and Ni-Cr-Ti ternary system by the CALPHAD method. Combining the experimental and ab initio calculated data on the enthalpies of formation of Ni-Ti compounds, a better description for Ni-Ti phases has been obtained. Based on the new assessments of the binary sub-systems and the recent experimental data on phase equilibria, a reassessment of the Ni-Cr-Ti system was carried out. Apart from the thermodynamic assessments, the interdiffusion coefficients for the fcc phase of the binary Ni-Ti were re-optimized and the ternary Ni-Cr-Ti system were determined experimentally over a temperature range from 1123 to 1273 K employing the diffusion-couple technique. Subsequently, atomic mobility data for the fcc phase of the Ni-Cr-Ti system were assessed and most diffusivity data were satisfactorily described.