Interfacial adsorption in ternary alloys

Interfaces of A-B-C ternary alloys decomposed into two and three phases are studied. The effect of the gradient energy coefficients <(kappa)over bar>(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-stare 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. II 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, <(kappa)over bar>(CC), can have a very strong influence on the degree of adsorption. In the alpha and beta two-phase regions, where alpha and beta are the phases rich in the majority components A and B, respectively, as <(kappa)over bar>(CC) increases, the adsorption of the minority component C in the alpha and beta interfaces decreases. Near a critical point, however, the degree of adsorption of minority component C is independent of the gradient energy coefficient. (C) 1999 Acta Metallurgica me. Published by Elsevier Science Ltd. All rights reserved.