ABSTRACT
This chapter explores the ways to estimate the nature and distribution of phases. In addition, the in-service behavior of complex systems which may involve solid, liquid, and vapors in contact can be better understood using knowledge of the phase equilibria. A phase equilibrium diagram is a graphical presentation of data that gives considerable information about a single compound or the nature of interactions between more than one compound. The state referred to as equilibrium in a materials system has been defined by the laws of thermodynamics as the condition when the free energy in the system is a minimum for a particular set of external conditions. Most of the phase equilibrium diagrams we have examined so far have a single liquid that is a homogeneous solution for all compositions above the liquidus. The chapter reviews some variations of two-component ceramic systems: simple eutectic, intermediate compounds, solid solution, liquid immiscibility, exsolution, and polymorphism.
