Experimental investigation and thermodynamic calculation of the phase equilibria in the Cu–Mo–Ni ternary system

The phase equilibria at 900 °C, 1000 °C, 1100 °C, 1200 °C and 1300 °C in the Cu–Mo–Ni system were experimentally determined by means of optical microscopy (OM), electron probe microanalyzer (EPMA) and X-ray diffraction (XRD) on the equilibrated alloys. The experimental results firstly found that the fcc-type miscibility gap exists at 900 °C, 1000 °C, 1100 °C and 1200 °C in the Cu–Mo–Ni system, and the solubility of Cu in the MoNi phase at 900 °C, 1000 °C, 1100 °C and 1200 °C are about 0.5 at.%, 1.5 at.%, 1.7 at.% and 4.0 at.%, respectively. The as-cast Cu20Mo20Ni60 (at.%), Cu20Mo30Ni50 (at.%), Cu10Mo60Ni30 (at.%), Cu70Mo10Ni60 (at.%), Cu20Mo60Ni20 (at.%) and Cu80Mo10Ni10 (at.%) alloys appear the separated macroscopic morphologies, which are caused by the liquid phase separation on cooling, while the as-cast Cu10Mo25Ni65 (at.%), Cu32Mo5Ni63 (at.%) and Cu30.7Mo6.3Ni63 (at.%) alloys show the homogenous microscopic morphologies. On the basis of the experimental data investigated by the present and previous works, the phase equilibria in the Cu–Mo–Ni system were thermodynamically assessed by using CALPHAD (Calculation of Phase Diagrams) method, and a consistent set of the thermodynamic parameters leading to reasonable agreement between the calculated results and experimental data was obtained.