Abstract
Thermodynamic properties of aluminum in molten silicon were measured by equilibrating silicon melts with mullite(s)-Al2O3(s), mullite(s)-SiO2(s), and SiO2(s) at 1,723 K and 1,773 K.Based on the results, (ａ) the standard free energy change for the oxygen dissolution into molten silicon, (ｂ) the activity coefficient of aluminum at infinite dilution referred to pure liquid, and (ｃ) the interaction parameters related to aluminum in molten silicon were determined to be：(ａ) 1/2 O2(g) = (mass%, H, in Si melt):Δ(ｂ) = -1.8(±0.1) (at 1,723 K), = -1.21(±0.01) (at 1,773 K)(ｃ) = 260(±10) (at 1,723 K), = 41(±1) (at 1,773 K eOAl = -0.63(±0.08) (at 1,723 K), eOAl = -0.57(±0.01) (at 1,773 K), respectively, for 1,723 K∼1,773 K.Finally, the stability diagram of the Si-Al-O system was established.
