Material Science Phase Diagram

1. Lecture – 2 05-Jan-2021 Unit - 1
Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore 1
Material Science
Phase Diagram

2. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Syllabus – Material Science
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Unit I: Phase Diagram
Phase diagram – Basic principles – Simple binary systems – Solid solutions – Eutectic systems- Application - Solid solution – Interstitial and substitution solid
solutions – Hume – Rothery electron compounds – Long range order theory of Bragg and Williams – Super lattices – Interstitial phase – Intermetallic compounds -
Elementary Ideas of corrosion – Oxidation – Creep and fracture
Unit II: Defects
Point defects – Scottky and Frenkel defects – Number of defects as a function of temperature – Diffusion in metals – Diffusion and Ionic conductivity in Ionic
crystals -Dislocations – Edge and screw dislocations – Burgers vector – Plastic deformation – Slip – Motion of dislocations under uniform Shear Stress - Stress
fields around dislocations – Density – Work hardening – Effect of grain size on dislocation motion –Effect of solute atoms on dislocation motion.
Unit III: Optical Properties, Dielectric Properties and Ferro Electrics
Color centers – Photo conductivity – Electronic transitions in Photo conductors – Trap, capture, recombination centers – Luminescence - Excitation and emission
Decay mechanisms Thallium activated alkali halides – Sulfide phosphorous - Ferroelectrics – Ferro electricity – General properties – Dipole theory – Ionic
displacements and the behaviour of BaTiO3 – Spontaneous polarization of BaTiO3 – Thermodynamics of Ferro electric transitions.
Unit IV: Elastic Behaviour, Polymer and Ceramics
An elastic and visco elastic behaviour - Atomic model of elastic behaviour - rubber like elasticity - An elastic deformation - Relaxation process - Model for visco
elastic behaviour - Polymers - Polymerization mechanism - Polymer structures - Deformation of polymers - Behaviour of polymers - Ceramics - Ceramic phases -
Structure - classes - Effect of structure on the behaviour of ceramic phases - composites.
Unit V: Laser Physics
Introduction – Interaction of radiation with matter - Spontaneous and stimulated emission – Conditions for oscillation to occur – Frequency of oscillation of the
system – Einstein co-efficient – Population inversion - Laser pumping Rate equations - Three level laser - Four level Laser – Nd:YAG Laser – He-Ne Laser -
Optical resonator – Types and modes of resonator – Oscillation - Threshold condition – The confocal resonant cavity – Theory – Spot size and beam divergence -
quality factor (Q) of an optical cavity.

3. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Syllabus – Unit-1 – Phase Diagram
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• Hume – Rothery electron compounds
• Long range order theory of Bragg and
Williams
• Super lattices
• Interstitial phase
• Intermetallic compounds
• Elementary Ideas of corrosion
• Oxidation
• Creep and fracture
• Phase diagram
• Basic principles
• Simple binary systems
• Solid solutions
• Eutectic systems
• Application
• Solid solution
• Interstitial and substitution solid
solutions

4. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Lecture Content
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• Phase diagram
• Basic principles
• Simple binary systems
• Solid solutions

5. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Definitions – Components, Phases
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Component - chemically recognizable species (Fe and C in carbon steel, H2O and
Sucrose in sugar solution in water). A binary alloy contains two components, a ternary
alloy – three, etc.
Phase – a portion of a system that has uniform physical and chemical characteristics.
Two distinct phases in a system have distinct physical and/or chemical characteristics
(e.g. water and ice, water and oil) and are separated from each other by definite phase
boundaries.
A phase may contain one or more components.
A single-phase system is called homogeneous, systems with two or more phases are
mixtures or heterogeneous systems.

6. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Phase Diagram
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A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to
show conditions (pressure, temperature, volume, etc.) at which thermodynamically distinct phases (such as solid,
liquid or gaseous states) occur and coexist at equilibrium.

7. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Types of Phase Diagram – 2D & 3D
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8. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Gibbs Phase Rule
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F = C – P + N
F - Degrees of freedom (No. of independent variables available to the system)
C - No. of components
P - No. of phases
N - No. of non-compositional variables (e.g.pressure & temperature)
F = C – P + 2
For routine processing of materials, we can consider the pressure to be fixed at 1atm:
F = C – P + 1

9. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Gibbs Phase Rule
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10. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Mixture – Solutions - Phases
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11. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Mixture – Solutions - Phases
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12. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Equilibrium Phase Diagram
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13. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Phase Diagram
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Phase diagram is a graphical representation of
all the equilibrium phases as a function of
temperature, pressure, and composition.
For one component systems, the equilibrium
state of the system is defined by two independent
parameters (P and T), (T and V), or (P and V).
Pressure-temperature phase diagram for H2O:

14. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Phase Diagram – Useful Information
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15. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Unary Phase Diagram
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16. Dr. R. Sarjila, Dept. of Physics, Auxilium College, Vellore Lecture – 2
Binary Phase Diagram
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17. Thank You
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