MEASUREMENT OF THERMODYNAMIC PROPERTIES OF AL-SB SYSTEM BY CALORIMETERS

The free energy, heat and entropy of mixing in a liquid Al-Sb alloy we re derived by combining heat contents of the alloy with the heat and e ntropy of formation of the equiatomic compound of AlSb at a reference temperature. The heat contents of the alloy were measured using a drop calorimeter in a temperature range from 800 to 1450 K and in a concen tration range of N-Sb from 0.05 to 0.95. The heat and entropy of forma tion of AlSb were determined respectively from the heat of solution me asurements at 773 K using a twin solution calorimeter and from the hea t capacity measurements in a temperature range from 4 to 300 K using a n adiabatic calorimeter. The obtained thermodynamic and phase diagram data for the Al-Sb system were analyzed using a Redlich-Kister polynom ial equation and the optimized parameters were derived as a function o f alloy composition and temperature.