A tutorial on flow diagrams: A tool for developing the structure of multicomponent phase diagrams

The tabular form of multiphase equilibria in temperature- or pressure-ordered sequence, often referred to as flow diagrams, shows the interrelations that exist among the various types or classes of equilibria in a system. These interrelations establish the structures of the various forms of phase diagrams. Flow diagrams have been used to simplify the presentation of complex ternary phase diagrams. However, they have been overlooked as a useful tool in predicting phase diagrams, in developing isotherms and isobars, and in teaching fundamentals of phase diagrams. In principle, flow diagrams can be applied to any system regardless of order. This tutorial will address the development of flow diagrams from simple binary diagrams through multicomponent systems, and will demonstrate application in determining phase diagrams and in establishing isotherms and isobars.