Interfacial adsorption in ternary alloys

Abstract

Interfaces of A–B–C ternary alloys decomposed into two and three phases are studied. The effect of the gradient energy coefficients κ ̄ II , I=A, B, C, on the interface composition profiles of ternary alloys is examined. The adsorption of component C in ternary alloys is obtained numerically by finding steady-state solutions of the nonlinear Cahn–Hilliard equations and by solving the two Euler–Lagrange equations resulting from minimizing the interfacial energy, and analytically near the critical point. It is found that the solutions from both numerical methods are identical for a two-phase system. In symmetric ternary systems (equal interaction energy between each pair of components) with a minority component C, the gradient energy coefficient of C, κ ̄ CC , can have a very strong influence on the degree of adsorption. In the α and β two-phase regions, where α and β are the phases rich in the majority components A and B, respectively, as κ ̄ CC increases, the adsorption of the minority component C in the α and β interfaces decreases. Near a critical point, however, the degree of adsorption of minority component C is independent of the gradient energy coefficient.