Experimental investigation and thermodynamic calculation of ternary Al–Ca–Mg phase equilibria

The ternary Al –Ca –Mg phase equlibria were investigated using X-ray diffraction methods, metallography, scanning electron microscopy with energy- and wave-length-dispersive X-ray microanalysis, and differential thermal analysis. The phase diagram was determined in the complete composition range. Large ternary solubilities were found for the binary phases CaMg , Al Ca and Al Ca . Microstructures of samples with compositions near the ternary monovariant eutectic L → CaMg + Al Ca show remarkable rod-like crystals that are identified as intergrowth between CaMg and Al Ca. A consistent thermodynamic model was developed using the Calphad method incorporating all experimental data. It was used to calculate all pertinent phase equilibria of the Al –Ca –Mg system.