The Application of the Boundary Theory of Phase Diagrams to the Quaternary and Higher Number Component Phase Diagrams

Abstract

In the text books dedicated to phase diagrams, isobaric phase diagrams are presented primarily as unary, binary and ternary phase diagrams. In the case of displays of two dimensional planes, the quaternary and higher component multidimensional phase diagrams can only be presented as sections or projections. The isobaric, multicomponent horizontal and vertical sections are the particular sections of importance. In order to discuss sections of these types, the boundary theory of phase diagrams is helpful. Moreover, higher dimensional phase diagrams can be inferred from lower ones, for example, in the calculation of isobaric ternary sections, one usually starts from the “side lines” of the binary systems; in these cases, the application of boundary theory is very enlightening. For the construction, application or learning/teaching of quaternary or more component system phase diagrams, the boundary theory for these phase diagrams is both useful and indispensable, since most people are usually not familiar with such complicated phase systems and their diagrammatic representation.