Experimental determination and thermodynamic assessment of the phase equilibrium states of an Al–Cr–Ce ternary system

Abstract

The phase equilibrium states of an Al−Cr−Ce ternary system were systematically investigated through experimental analysis and thermodynamic modeling. The 800 and 1000 °C isothermal sections of the Al−Cr−Ce ternary system were constructed using the equilibrium alloy method based on the results of scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction analyses. Fourteen three-phase equilibrium regions were confirmed and two three-phase equilibrium regions were speculated at 800 °C, whereas 10 three-phase equilibrium regions were determined and one three-phase equilibrium region was speculated at 1000 °C. Two new ternary compounds—τ3 and τ4—were discovered, and it was found that the τ3 phase was stable at both 800 and 1000 °C; however, the τ4 phase was only stable at 800 °C, and it disappeared at 1000 °C. In addition, four types of primary solidification regions—τ1, Al₄Ce, Al₂Ce, and (Cr)—were detected. Based on the experimental results obtained in this study and the data available from previous literature, the thermodynamic modeling of the Al−Cr−Ce ternary system was performed using the CALPHAD method, and a set of self-consistent thermodynamic parameters between the experimental and calculated results was satisfactorily obtained for the Al−Cr−Ce ternary system.