DETERMINATION OF THE ACTIVITIES OF MAGNESIUM IN LIQUID MAGNESIUM–TIN ALLOYS BY VAPOR PRESSURE MEASUREMENTS

Abstract

The vapor pressure of liquid magnesium–tin alloys has been measured between 780 °C and 1010 °C using the isopiestic method.Activities of magnesium were obtained at 800 °C, 910 °C, and 940 °C. Activities of tin showed a negative departure from ideality, and those of magnesium, both negative and a slight positive departure.Partial heats and entropies of mixing were calculated, and values are negative for most of the composition range. Partial free energies of mixing for the entire composition range showed negative values. Integral heats, entropies, and free energies were calculated from the partial quantities. These values were negative, indicating an ordered liquid alloy.