ABSTRACT
Examples of actual systems containing both binary and ternary intermediate phases are common, for example in metallic and ceramic systems. In practice, the term quasi-binary is commonly applied to cases where some degree of solid solubility exists, and if the extent of the solubility is small there is likely to be little deviation from the strictly quasi-binary case. The presence of one or more intermediate phases in addition to three primary solid solutions leads to many possible forms of ternary system. XC can be termed a ‘quasi-binary’ section or system; it has the characteristics of a binary system in that during the course of solidification of any alloy lying in it, the compositions of liquid and solid remain in the section. That is all tie-lines, and the three-phase equilibrium line all lie in the plane of the section.
