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A B C
Reading Off Compositions

  

A composition is determined by
calculating the percentage
of each component.
The sum of the percentage
of each component is 100%.
A B C 30% 50% 20% X

  

Determining the proportion of
component B in alloy of
composition X.
%B = X B ac Bac 5 10 =50% x100
A B C B X B ac X
ac B 10cm ac X B 5cm

  

B A C X C X C ab A X A bc
10cm 3cm 10cm 2cm A bc X A bc C ab X C ab
%A = x100 X A bc Abc X C ab Cab 3 10 =30% 2 10 =20%
Similarly, proportions of A and C
can be determined.

  

  
The method shown previously will
always give the correct compostion
but it can be quite tedious.

To simplify things, some ternary
phase diagrams are plotted with
a reference grid to make it
easier to read off compositions.

0 10 20 80 70 60 50 40 30 100 90 0 10 20 80 70 60 50 40 30 100 90 100 90 20 30 40 50 60 70 80 10 0 A B C X