Phase Diagrams

· The Gibbs function curves are composed from entropy and enthalpy contributions.
· The entropy term contains both the thermodynamic entropy of the pure materials and the entropy of mixing.
· a) No mixing: S_S = S_A + X_B S_B

· b) Mixing only: S_M = k Ln{N!/ N_A! N_B!}

· c) Total entropy: S = S_S + S_M

From: Brophy, Rose, & Wulff, "Thermodynamics of Structure," Wiley (1964)