The first parameter required in order to describe the constitution of any alloy is the types of phases present.
This is very straightforward when all the phase regions are marked as it is simply a case of reading the labels.
Sometimes only the single phase regions are annotated. Here, the phases present at any point in a two-phase region can be obtained by:
- drawing a tie-line across the two-phase region
- reading the names of the single phase fields connected by the tie line.