Activity of magnesium in liquid Ag–Mg alloys

Activity measurements of magnesium in liquid Ag–Mg solutions were carried out at 1573, 1673, 1773 and 1823 K using two different techniques. While most measurements were carried out using the vapor pressure method at 1573 and 1673 K, a number of measurements were made at 1773 and 1873 K using the gas equilibration technique. The latter method was used mostly for obtaining Ag–Mg solution at very low Mg contents. It was found that magnesium had a negative deviation from ideality in Ag–Mg solutions. The excess Gibbs energy of Ag–Mg solutions seemed to have a quite weak temperature dependency in the temperature region studied. The excess Gibbs energy of Ag–Mg solution can be described as; ΔGMg−AgXS=XMgXAg(−66583+23970(XAg–XMg)) J/mole  between 1573 and 1823 K

► Experimentally determined activities of Mg in liquid Ag–Mg alloys using two techniques.
► Mg exhibits negative deviation from ideality.
► The best data fit was found using the sub-regular model to describe the thermodynamics of liquid Ag–Mg alloys.