The document discusses phase diagrams and their applications. It defines key terms like phase, pure substance, and phase changes that can occur through varying temperature and pressure. Common phase changes discussed are solid-liquid, liquid-vapor, and solid-vapor. The diagram shows lines that represent phase boundaries and points like the triple point. Applications include determining alloy properties, designing heat treatments, and solving performance issues for commercial alloys.

1. BY
150070204

2. Phase is Homogenous, physically distinct and mechanically
separable part of the system
If you look at the diagram, you will see that
there are three lines, three areas marked
"solid", "liquid" and “Vapour", and two special
points marked "C" and "T".
Pure substance- It is a substance constant
Chemical composition throught its mass .
it may exist in one phase or more than one phase

3. At point 1 in the diagram, the substance would
be a solid because it falls into that area of the
phase diagram. At 2, it would be a liquid; and at
3, it would be a Vapour (a gas)
Moving from solid to liquid by changing the temperature:
If increases the temperature while keeping the
pressure constant - as shown in the figure. As
the temperature increases to the point where
it crosses the line, the solid will turn to liquid
(solid melts at higher temperature)
(fusion line)

4. Moving from solid to liquid by changing the pressure:
If the decrease the pressure on a solid at
constant temperature
Moving from liquid to Vapour:
The liquid will change to a Vapour - it boils -
when it crosses the boundary line between the
two areas
As the pressure increases, so the boiling point
increases.
(Vapourisation line)

5. In liquid-vapour equilibrium curve has a top limit at that
point C in the phase diagram. It is called critical point. The
temperature and pressure corresponding to this are known
as the critical temperature and critical pressure.
If you increase the pressure on a gas (Vapour) at a
temperature lower than the critical temperature, you will
eventually cross the liquid-Vapour equilibrium line and the
Vapour will condense to give a liquid
Shortcut Def
the intersection of saturated liquid
line and saturated Vapour line

6. Moving from solid to Vapour (sublimation line)
If the temperature and pressure fell exactly on same line, there would
be solid and Vapour in equilibrium with each other - the solid would
be subliming. (Sublimation is the change directly from solid to Vapour
or vice versa without going through the liquid phase.)
The triple point
At point T on the diagram is called the triple point.
The combination of temperature and pressure
where all three phases are in equilibrium
together. That's why it is called a triple point.
Def-
The intersection of fusion line, Vapourisation line and sublimation line
Is called triple point

7. 2-D Representation of phase diagram

8. 3-D Representation of phase diagram

9. Binary phase diagram
On a two component or binary diagram three variables can be
represented. These are generally pressure (P), temperature (T)
and compositional changes (X)
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.Ex-
isomorphous systems

10. Crystal phase diagrams

11. Types of phase diagrams
1) ISOMORPHOUS SYSTEMS
2) EUTECTIC SYSTEMS
3) PARTIAL EUTECTIC SYSTEMS
4) LAYER TYPE SYSTEMS
1) ISOMORPHOUS SYSTEMS
THESE diagrams are loop type and are obtained for two metals
Having complete solubility in the liquid state as well as solid state
Ex – cu/Ni, au/ag

12. Eutectic systems –
These diagrams are obtained for having
complete solubility in the liquid state and
complete insolubility in the solid state
Ex- Pb/As ,bi-cd, th -ti

13. PARTIAL EUTECTIC SYSTEMS
These diagrams are obtained for two metals which
have complete miscibility in the liquid state and
Partial solubility in the solid state
Ex- AG/CU , PB/SN, SN/BI

14. Layer type systems
These diagrams are obtained for two metals which have
Complete insolubility in the liquid as well as solid state
Ex- CU/MO,CU-W.
Other types of phase diagrams

15. Phase Diagrams of Water and Carbon
Dioxide

16. Pure iron: 3 solid phases
BCC ferrite (α)
FCC Austenite (γ)
BCC δ
Beyond 6.7% C
cementite (Fe3C)
Eutectic: 4.3% C
L - γ + Fe3C
(L -solid + solid)
Eutectoid: 0.76% C
γ + α + Fe3C
(solid - solid + solid
IRON-CARBON (Fe-C) PHASE DIAGRAM

18. (1) Development of new alloys
(2) fabrication of these alloys into useful
configurations,
(3) Design and control of heat treatment
procedures for specific alloys that will
produce the required mechanical, physical,
and chemical properties,
(4) solving problems that arise with specific
alloys in their performance in commercial
applications
Applications of phase diagrams

19. Industrial applications
1)Age-Hardening Alloys.
2)Austenitic Stainless Steel.
3)Permanent Magnets.

20. Phase diagrams are useful tools to determine
The number and types of phases,
The wt% of each phase,
and the composition of each phase for a given T and
composition of the system phase
Alloying to produce a solid solution usually
Increases the tensile strength (TS)
--decreases the ductility
SUMMARY

21. THANK
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