Thermodynamic properties of aluminum, magnesium, and calcium in molten silicon

The thermodynamic properties of aluminum, magnesium, and calcium in molten silicon were investigated using a chemical equilibration technique at 1723 to 1848 K, 1698 to 1798 K, and 1723 to 1823 K, respectively. The activity coefficient of aluminum in molten silicon was determined by equilibrating molten silicon-aluminum alloys with solid Al(2)O(3) and Al(6)Si(2)O(13), that of magnesium was determined by equilibrating molten silicon-magnesium alloys and MgO-SiO(2)-Al(2)O(3) melts doubly saturated with MgSiO(3) and SiO(2), and that of calcium was determined by equilibrating molten silicon-calcium alloys with SiO(2)-saturated CaO-SiO(2) melts. The activity coefficients at infinite dilution relative to the pure liquid state were determined as follows: log gamma(Al(l)in Si)degrees = -1570/T + 0.236 (1723 to 1848 K) log gamma(Mg(l)in Si)degrees = -4900/T + 1.96 (1698 to 1798 K) log gamma(Ca(l)in Si)degrees = -7670/T + 1.53 (1723 to 1823 K).