The 400 °C isothermal section of the Mg–Al–Ca system

The Mg–Al–Ca system is experimentally investigated at 400 °C using diffusion couples and key experiments. Phase relations and solubility limits were determined for binary and ternary phases using EPMA and XRD techniques. The Mg2Ca, (Al,Mg)2Ca phases were found to form substitutional solid solutions where Al substitutes Mg atoms. The Al2(Mg,Ca) and Al140Mg89 phases form solid solutions where Ca substitutes Mg atoms. The Al2Ca phase has a complex solid solution where Mg substitutes both Al and Ca atoms. No ternary solubility was found for the Al4Ca phase. Based on the results of the phase analysis and experimental literature data, the isothermal section of the Mg–Al–Ca phase diagram at 400 °C has been constructed.