Experimental investigation and thermodynamic optimization of the Al-Ni-Sc ternary system

Phase equilibria of the Al-Ni-Sc system were investigated by combination of key experiments and thermodynamic modeling. The isothermal sections of the Al-Ni-Sc ternary system in the (Al, Ni)-rich region at 873K and 673K were investigated using the electron probe microanalysis (EPMA) and X-ray diffraction (XRD). The solubilities of the binary phases in the ternary system were measured. According to the experimental results in this work and related literature, the Al-Ni-Sc ternary system has been optimized by means of the CALPHAD (CALculation of PHAse Diagrams) method. Isothermal sections at 1273, 1173, 873 and 673 K were reproduced. The calculated thermodynamic and phase equilibria data for the ternary system agree well with the experimental data. This work can be used as a basis for the multi-component thermodynamic database of Al-based alloys.