ABSTRACT
Systems containing three components are called ternary systems. A condensed ternary system can be bounded by any type of binary system. The ternary system is also a simple eutectic type where boundary lines from the binary eutectic invariant points meet in the interior of the system at the ternary eutectic invariant point and outline three liquidus surfaces of primary crystallization of the "end-member" components. The changes which occur during the equilibrium cooling of a melt of a given composition and the quantitative isoplethal analysis are usually worked out through the use of a plane projection of the liquidus surface. However, the rules of construction which are used on the plane projection have been derived from the three-dimensional solid representing the ternary system. The sequence of reactions may be better understood by considering isothermal and vertical sections through the solid model of the ternary system.
