Experimental investigation and thermodynamic modeling of the Al–Dy–Zr system

Abstract

The Al–Dy–Zr ternary system has been experimentally studied and thermodynamically assessed to contribute to the development of novel heat-resistant aluminum alloys. Using equilibrated alloys, the isothermal section of this ternary system at 873 K has been established by means of scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD). Experimental information on vertical sections was obtained by performing differential scanning calorimetry (DSC) analysis on selected annealed samples and that on liquidus projection was extracted from the as-cast samples by observing the primary crystallization phases. In addition, the first-principles method was employed to calculate the enthalpy of formation of metastable compounds involved in the sublattice model. Based on the experimental data and first-principles calculation results in this work, the Al–Dy–Zr system was optimized within the framework of the calculation of phase diagram (CALPHAD) method. Good agreement was found between the experimental data and the thermodynamic calculation results, which indicates that the thermodynamic description developed in this work is reliable.