A look at the Carbon-Iron-Phosphorus equilibrium diagram
A look at the Carbon-Iron-Phosphorus ternary diagram
C-Fe-P ternary diagram
This page is maintained by skip.williams@yahoo.com
I hope to return soon to add a list of sources.
All temperatures are Celsius
The ternary diagram
The rose tinted region is the Alpha iron (ferrite).
The yellow tinted region is Gamma iron (austenite).
The tan tinted region has two phases, meaning that both the alpha and gamma phases are present.
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The isothermal section at 1100 ºC
A liquid phase is present in the grey tinted areas.
The single alpha phase is only present as a thin sliver.
The 0.3%C Isopleth
A slice through the ternary diagram at 0.3 wt% Carbon reveals the phases that are present across the range of phosphorus and temperature. The lever rule cannot be used with an isopleth to determine the weight% of each phase in a multiphase region.
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The 0.3% Carbon-Iron-Phosphorus Isopleth intersecting the C-Fe binary diagram
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Tie-Lines in the two phase region
The composition of the alpha and gamma phases in the two phase region can be determined from tie-lines.
Tie lines at 1100°C
modified from Mehta, Studies on Weldability of Powder-Processed Fe-0.35P-0.15C; after Lindskog, Tengzelius and Kvist, 1977
Tie lines at 900°C
The end for now
When I have a chance I'll come back and add information about the type of phase transformations the different alloys pass through as they are cooled or quenched.
