Capillary Properties and Thermodynamics of the Surface Layer of Ti–Cu and Zr–Cu Melts

Abstract

The thermodynamic theories of surface tension of solutions, Gibbs adsorption equation, surface stability condition, and experimental data (concentration de-pendences of surface tension and molar volume of alloys) and the thermodynamic activity of components over volume are used to determine the composition, integral and excess Gibbs energy of formation, and activity of components in the surface layer of Ti–Cu and Zr–Cu melts. The solutions formed in the surface layer and over volume have a negative deviation from Raoult’s law. The copper adsorption curve for alloys has a slanting maximum. The composition of the surface layer insignificantly differs from that of the volume. The Gibbs energies of solution formation and their excess values at all concentrations in the surface layer are negative. They are lower than thermodynamic values over volume.