相律 Phase rules Phase diagrams are extremely useful for systems with multiple components, and serve to describe physical and chemical equilibria over a range of different compositions, as well as points where substances are mutually miscible, or even when a system has to be brought to a specific set of conditions for equilbrium to exist(e.g, pressure, temperature and composition) Phase diagrams are very important in the development of alloys ceramic materials steels ■ semiconductors plastIcs superconductors cosmetics petroleum product separations food products glasses All phase diagrams are developed around one relationship, the phase rule, which was derived by J.W. Gibbs-it can be applied to a wide variety of systems Phase diagrams: pictorial way of understanding the properties of a system相 律 Phase Rules