TABLE OF CONTENTS In the previous chapter the bases for the development of an understanding of the relationship between free energy composition diagrams and phase diagrams were explored. We shall in Section A below attempt to provide an understanding of the factors responsible for the effect of composition on the solid/liquid equilibria; the influence of intermediate phases on phase diagrams; the concept of metastable phases; the development of phase diagrams from the temperature dependence of the free energy composition curves; and, finally, methods for the prediction of ternary phase diagrams. In Section B we shall present first the basic principles regarding heterogeneous chemical equilibria and then we shall relate these principles to ternary phase diagrams and equilibrium between contacting compounds.
From the condition governing the equilibrium between phases, the relations for the solid liquid equilibrium in a binary alloy can be set down as follows
But, G i = xsG i + oG i + RT ln X i (actually, the latter relation acts to define the excess molar free energy of component i, xsG i, in terms of the partial molar free energy of component i and the molar free energy of component i in its pure state, oG i). Substitution into equation 3.1 and solution of the resulting equations yield
Let us postpone consideration of the...
