Alkemade triangle

Alkemade lines are also called in many different ways including conjugation lines and joins. Both Alkemade lines and Alkemade triangles (composition triangles produced by Alkemade lines) are of use in die understanding of ternary systems. They play an essential role in understanding crystallisation or heating paths ... 

As the whole diagram is an Alkemade triangle and point e is the ternary eutectic, all crystallisation curves of this ternary system should terminate at this ternary eutectic. However, binaty liquid compositions such as points p and s terminate their respective binary eutectic, e and a. 

As point p lies in the Alkemade triangle C-AC-BC, the final solid phases in equilibrium should be C, AC and BC. From the figure given below,... 

At/ the final solidification takes place through a peritectic reaction AC and BC crystallise out together at the expense of liquid and portion of C. This can easily be seen from die Alkemade triangle C-AC-BC. During the peritectic reaction, the mean solid composition moves from k to p. 

At completion of the solidification at point g, the final solid phases in equilibrium are AC, BC and B since the mean composition of the system lies within the Alkemade triangle AC-BC-B as mentioned earlier. 

Figure 3.6 Compatibility triangles (dashed lines) superimposed on the stability fields 1 to 10, and directions of falling temperatures on the phase boundary curves (arrowheads), determined according to the Alkemade theorem.

Figure 3.26 Cotectic (compatibility) triangles (solid lines) in the ternary diagram Ca0-Al203-Si02 (mass%). In the Si02-rich portion, three important triple points are indicated at the intersection of the phase boundaries (dashed lines). The arrows show the direction of falling temperatures according to the Alkemade theorem...

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