3. Immiscibility in glass

3.1 Phase separation

In a binary system, stable phase separation results in the appearance of two immiscible liquids of different compositions. The separation results from the fact that the free enthalpy exhibits two respective minima as a function of composition X. The tangent common to the minima determines the composition of the phases in equilibrium. If the immiscibility domain extends into the existence domain of the crystalline phases, we obtain an invariant called monotectic corresponding to an equilibrium of phases liquid I (L _I ) - liquid II (L _II ) - crystalline solid solution α (figure 15...