Isothermal sections of the Mg-rich corner in the Mg-Sn-Y ternary system at 300 and 400 °C

The phase equilibria of the Mg-rich corner in the Mg-Sn-Y ternary system at 300 and 400 degrees C have been determined through equilibrated alloy method by means of X-ray diffraction (XRD), scanning electron microscopy with assistance of energy dispersive spectroscopy of X-ray (SEM-EDS), and thus the isothermal sections of this ternary system have been constructed. The equilibrium phase relations have no change with increase from 300 to 400 degrees C, and there are both four intermetallic compounds in equilibrium with the alpha-Mg solid solution at the two temperatures, i.e. Mg2Sn, MgSnY, Sn3Y5 and Mg24+xY5. It is interesting to find that either Y or Sn can be soluble in the alpha-Mg solid solution but they are not simultaneously soluble. The solubility of Mg in the compound Sn3Y5 increases with the temperature from 300 to 400 degrees C. According to the phase relations and high-melting-point characteristics of these intermetallics in this ternary system, such as Sn3Y5 phase, etc., it is expected that the Mg-Sn-Y-based alloy could be a promising creep resistant alloy by appropriate alloy design and processing. (C) 2009 Elsevier B.V. All rights reserved.