Experimental investigation and thermodynamic assessment of the Al-Er system

The phase equilibria of the Al-Er binary system have been investigated through both experiments and CALPHAD assessment. The phase relationship in the compositional range of 0-50 at. % Er was experimentally redetermined using scanning electron microscopy (SEM) with Energy Dispersive Spectroscopy (EDS), electron probe micro analysis (EPMA) with wavelength dispersive spectrometer (WDS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results confirmed the existence of the Al3Er phase (Al3Ho-type structure) with limited homogeneity range in the Al-Er system. It was formed through the peritectic reaction L + Al2Er <-> Al3Er at 1105.3 +/- 2.4 degrees C. While the Al17Er2 phase was proved to be metastable in the present work. A full thermo-dynamic optimization of the Al-Er binary system has been carried out by utilizing the current experimental data as well as all available results in the previous publications. A set of self-consistent thermodynamic parameters for the Al-Er system was established. The calculated phase diagram and thermodynamic properties agree well with the available data. The artificial inverted liquid-liquid miscibility gap at high temperature in the previous evaluation is removed.

Automated summary

The phase equilibria of the Al-Er binary system were investigated through experiments and CALPHAD assessment. The existence of the Al3Er phase and the metastability of the Al17Er2 phase were confirmed. A set of self-consistent thermodynamic parameters for the system was established, and the calculated phase diagram and thermodynamic properties agreed well with the available data. The artificial inverted liquid-liquid miscibility gap at high temperature in the previous evaluation was removed.