Experimental investigation and thermodynamic modelling of the Mg-Al-rich region of the Mg-Al-Sr System

A thermodynamic description of the Mg-Al - Sr ternary in the Mg- Al-rich region was developed based on the microstructures, the crystal structures and compositions of the phases in three samples in the as-cast and 673 K annealed states. The gross compositions of the three alloys were identified for investigation based on a calculated isotherm using the description obtained from those of the constituent binaries via extrapolation. The calculated liquidus projection using the developed description was found to be consistent with the primary phases of solidification obtained from two additional alloys in the as-cast state. In addition, the model-calculated isotherm and liquidus projection are able to rationalize results reported in a recent publication for this ternary. This paper demonstrates the power of using a preliminary calculated phase diagram for selecting key alloys for experimentation, on basis of which a reliable thermodynamic description can be developed. © 2006 Carl Hanser Verlag, München.