The theorem of corresponding relation between neighboring phase regions and their boundaries in phase diagrams (I)

Several fundamental concepts in phase diagrams have been discussed. The theorem of corresponding relation between the number of different phases in the neighboring phase regions Φ and the dimension R 1 of their phase boundary in the phase diagrams is derived from the phase rule. The five corollaries of this theorem for isobaric phase diagrams are derived also. By applying this theorem and its corollaries, the following results can be obtained. Both the boundary rule and contact rule of phase regions in phase diagrams may be deduced. The ten empirical rules for constructing the complex ternary isobaric phase diagrams from phase diagram units may be put on a theoretical basis. The relation between neighboring phase regions and their boundary in phase diagrams of one-, two-, three- and four-components of all types and in the different horizontal and vertical sections of ternary phase diagrams may be explained without introducing any supplementary concept.