抄録
Activity of lithium in molten Al-Li alloy up to 3.3at%Li has been measured in the temperature range between 950K and 1, 100K. Method used is based on measuring the EMF of Li ILiCl IA1-Li cell in which all the materials are liquid states. Al-Li alloy is made by addition of lithium electrolytically into molten aluminum and Li electrode is prepared by the deposition of lithium also electrolytically on the tungsten wire. Potensials of the electrodes are measured against Ag/AgCl electrode which is in mullite tube and shows very stable potential. EMF of the cell is determined as the difference between the potentials of Al-Li and Li electrodes measured vs. Ag/AgCl electrode. As all the sequence of procedures, preparing electrodes and measuring electrode potentials, are performed in molten LiCl, the electrodes are not affected by the atmosphere and are kept clean. Therefore, highly reliable and precise measurements have been carried out.
Activity coefficients of Li in the alloy are 0.21 and 0.28 at 973K and 1, 073K, respectively if Henry' law is assumed in the composition range measured. However, the activity coefficient slightly depends on the composition. Then thermodynamic quantities, partial molar enthalpy, partial molar entropy and excess partial molar entropy have been determined by using the results obtained, and the activity coefficient has been determined as a function of composition and temperature.
