Phase equilibria, thermodynamics and solidification microstructures of Mg-Sn-Ca alloys, Part 1: Experimental investigation and thermodynamic modeling of the ternary Mg-Sn-Ca system

The phase equilibria of the Mg-Sn-Ca system for the entire composition and temperature ranges have been clarified based on the Calphad method. To obtain a reliable thermodynamic description, we performed key experiments for the phase boundary data and also utilized the first-principle results of the finite-temperature properties for the binary and ternary compounds. Experimental works for the phase equilibria, which consist of thermal, crystallographic and microstructural analyses, and the thermodynamic modeling combined with finite-temperature first-principle calculations are reported. The satisfying agreements between the experimental and calculated results support the reliability of the proposed thermodynamic description. The phase diagram for overall composition and temperature ranges of the ternary system based on the thermodynamic calculations is presented. In a second study this result is applied to obtain details of the phase formation during solidification for practically important Mg-rich as-cast alloys. (C) 2007 Elsevier Ltd. All rights reserved.