Polythermal projection

The first method consists of a polythermal projection of all features (liquidus, etc) down onto the base composition triangle. 

The figure below shows such a polythermal projection of a simple ternary eutectic system without solid solution like the one represented by the figure above. 

The polythermal projection is generally given with constant temperature lines as shown in... 

In order to solve this problem, the polythermal projection method was discussed in the previous section (Section 4.3.2). In this section, the other method, namely, two dimensional isothermal diagrams are discussed. 

Polythermal projections of the liquidus discussed in section 4.3.2. do not provide information on the compositions of solid phases if solid solutions or non-stoichiometric compounds are formed at equilibrium. For providing this information, the method of isothermal section is particularly useful. The following figure represents a simple ternary eutectic system with terminal solid solutions formed. 

Figure 11.6 shows an example of the phase diagram for a reactive system, in which a compound C is formed from components A and B. An isothermal cut and the polythermal projection are also shown. Such a phase diagram can be obtained via a reaction invariant projection of a higher-dimensional simple eutectic phase diagram. AS and BS are binary nonreactive eutectics, since their presence is not affected by the reaction, while ACSb and BCSa are ternary reactive eutectics. Similar... 

In the polythermal projection of the liquidus surface, monovariant liquidus grooves separate phase regions of primary crystallization and, where available, isothermal lines eontour die liquidus surfaee (see Fig. 3). 

Figure 17.33 Polythermal projection of the liquidus surface of component A in Figure 17.31.

The granite system diagram is shown as a polythermal projection in Figure 17.35. 

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