Types of cooling curve

1. COOLING CURVE
Unit -1

2. Cooling curve
• The solidification of molten metal is plotted as
a graph is called cooling curve.
• X – axis – Time
• Y – axis -Temperature

3. Types of cooling curve
1. Cooling curve for Pure metal or compound
(liquid , solid)
2. Cooling curve of a binary solution (liquid,
solid ,liquid + solid)
3. Cooling curve of a binary Eutectic system
(liquid, solid ,liquid + solid)

4. .

5. 1.Cooling curve for Pure metal or
compound
PQ -- Molten Metal Looses Its Temp
Q – Starting Point For Crystal Structure
QR –Latent heat is liberated Temp remains constant
RS – Solid metal formation

6. 2.Cooling curve of a binary solution
PQ -- Molten Metal Looses Its Temp
Q – Starting Point For Crystal Structure
QR –The slope of cooling curve will change due to evolution of latent heat of
crystallization.
RS – Solid metal formation

7. 3.Cooling curve of a binary Eutectic system
PQ -- Molten Metal Looses Its Temp
Q – temperature drops along QR and crystallization of one component starts.
R –the liquid composition reaches such level that two components crystallise
simultaneously from the solution and temperature remains constant until all
the liquid solidifies.
ST – Solid metal formation

8. CONSTRUCTION OF PHASE DIAGEAMS

10. Interpretation of phase diagrams
• Using a phase diagram, one can obtain at least
the following three transformations.
1. The phases that are present
2. The composition of each phase
3. The amount of each phase present.

12. Types of Equilibrium Phase Diagram
• Plot the composition of phases as a function
of temperature in any alloy system under
equilibrium conditions.
1. Phase diagrams for complete solid solubility
2. Phase diagrams for partial solid solubility
3. Phase diagrams containing reactions

13. 1. Phase diagrams for complete solid
solubility
• Two elements are completely soluble in each
other in both in liquid and solid states is
known as isomorphous system.
Examples
Cu-Ni System
Sb-Bi System
Au-Ag System
Cu-Au System

15. 2. Phase diagrams for partial solid
solubility
• If the two metals A and B are not completely
soluble through all ranges in composition, the
second phase will form at grain boundaries.
Examples
Cu-Ag System
Al-Cu System

17. 3. Phase diagrams containing reactions
• Eutectic reaction
• Peritectic reaction
• Eutectoid reaction
• Peritectoid reaction

18. Eutectic reaction

20. Peritectic reaction

22. Eutectoid reaction

24. Peritectoid reaction

25. Summary