Experimental investigation and thermodynamic modeling of the Ce-Si system

Phase equilibria and thermodynamic properties of the Ce-Si system were studied experimentally by investigating a Si/(Ce,Si) diffusion couple and thirteen Ce-Si alloys. X-ray diffraction (XRD), electron probe micro-analyzer (EPMA), differential thermal analysis (DTA) and high temperature reaction calorimetry (HTRC) were utilized. A phase with close composition of CeSi1.34 and the decomposition temperature of 1469 K is detected. The eutectic reaction liquid ↔ (Si) + CeSi2 is observed to occurs at 1502.6 K. The enthalpy of formation of CeSi1.68 was measured to be −70 ± 6 kJ mol-atoms−1. A thermodynamic modeling of the Ce-Si system was then performed by considering the reliable literature data and the present experimental results. A substitutional solution model was used for the description of the liquid phase, and all of the compounds are treated as stoichiometric ones. The calculated phase diagram and thermodynamic properties using the obtained thermodynamic parameters are in good agreement with the experimental data.