Phase equilibria and solidified microstructure in Cu–Cr–La ternary system via experimental investigation and thermodynamic calculation

The phase equilibria and solidified microstructure of Cu–Cr–La system were investigated by a combination of key experiments and thermodynamic calculations. Six Cu–Cr–La ternary alloys were utilized to determine the solidified microstructure, isothermal section at 850 °C and phase transition temperatures along 5.0 at.% La by means of X-ray diffraction, scanning electron microscopy, electron probe micro-analysis and differential scanning calorimetric techniques. By considering the present measured equilibrium data, the thermodynamic description for the Cu–Cr–La system was established via CALPHAD approach. The calculated phase relationship and phase fractions in equilibrium state shows a satisfactory agreement with the determined data. After that, the non-equilibrium solidification curves in different series Cu–Cr–La alloys were simulated with the Scheil–Gulliver model. The effects of La or Cr additions on the solidification sequences, phase transition temperatures and phase fractions in Cu–Cr–La alloys were analyzed. It is believed that the present work offers a theoretical basis for the novel design of Cu–Cr–La alloys.