The Arrhenius equation and associated hypotheses are used to show how the heat of formation influences the relative fractions of binary components in tri-phase ceramic films. With a simple expression the heats of formation under different volume fractions and temperature predicted. This expression can be used to solve the formation condition of each film's component under non-equilibrium conditions and can also be used to understand growth mechanisms in the films. (C) 2002 Elsevier Science B.V. All rights reserved.