Thermodynamics of aluminum-barium alloys

Abstract

The activity of barium in liquid Al-Ba alloys (X_Ba ≤ 0.261) at 1373 K has been determined using the Knudsen effusion-mass loss technique. At higher concentrations (X_Ba ≥ 0.38), the activity of barium has been determined by the pseudo-isopiestic technique. Activity of aluminum has been derived by Gibbs-Duhem integration. The concentration-concentration structure factor of Bhatia and Thornton^[22] at zero wave vector has been computed from the thermodynamic data. The behavior of the mean-square thermal fluctuation in composition indicates a tendency for association in the liquid state. The associated solution model with Al₅Ba₄ as the predominant complex has been used for the description of the thermodynamic behavior of liquid Al-Ba alloys. Thermodynamic data for the intermetallic compounds in the Al-Ba system and the enthalpy of mixing in liquid alloys have been derived using the phase diagram and the Gibbs' energy of mixing of liquid alloys.