INTRODUCTION
TWO COMPONENT OR BINARY SYSTEMS
On a two component or binary diagram three, variables can be represented. These are generally pressure (P), temperature (T) and compositional changes (X) on a two dimensional diagram.
To graphically represent a Binary diagram one variable must be kept constant, which is usually P, and the phase diagram is plotted as a T-X diagram for a specific Pressure.
At constant P there are 8 possible types of Binary Diagrams which are of interest to petrologist.
Binary Diagrams Examples I
Binary Diagrams Examples II
We will look at crystallization and melting relationships in 3 of these types.
- Simple Eutectic, no solid solution (#1 on Examples I)
- Incongruently melting phase, No SS (#3 on examples I)
- Complete to Partial Solid Solution (#5, #6 and #7 on Examples II).
