This document discusses alloys and phase diagrams, which are important concepts in metallurgy and materials engineering. It covers the constitution of alloys including solid solutions, Hume-Rothery's rules for solid solubility, and the different types of solid solutions. The document also discusses phase diagrams, including one-component phase diagrams for pure substances and phase diagrams for partially solid solutions that can have up to six phases. Phase diagrams are critical tools for understanding phase transformations and equilibrium conditions in alloy systems.

1. ME8491--ENGINEERING
METALLURGY

2. UNIT I --ALLOYS AND PHASE
DIAGRAMS
Constitution of alloys – Solid solutions,
substitutional and interstitial – phase diagrams,
Isomorphous, eutectic, eutectoid, peritectic, and
peritectoid reactions, Iron – carbon equilibrium
diagram. Classification of steel and cast Iron
microstructure, properties and application.

3. UNIT-I
CONSTITUTION OF ALLOY
AND PHASE DIAGRAMS

4. IMPURITIES IN SOLIDS
• Impurities are always present in all materials.
ALLOY:
• It is a mixture of two or more metals. Metal and
a non metal.

5. SOLID vs LIQUID SOLUTON

6. HUME ROTHERY’S RULES
• The solute and solvent follows the following
general rules:
1. Size factor (similar size)
2. Crystal structure(same crystal structure)
3. Valence (same valence)
4. Electronegativity (approximately same electro
negativity)

7. TYPES OF SOLID SOLUTIONS
1. Substitutional solid solutions
(mixture of two elements, substitute for a
parent element)
a) Random b)Ordered
2.Interstital solid solutions
(the solute atom fit in to the space between
solvent and parent atom)

10. PHASE DIAGRAM

11. PHASE DIAGRAM OF PURE SUBSTANCE
(ONE COMPONENT PHASE DIAGRAM)

12. GIBBS PHASE RULE
• F=C-P+2
• Where, c= number of components
• P= number of phases

13. PHASE DIAGRAM FOR PARTIALLY SOLID
SOLUTION (16 mark)
• SIX PHASES IN THE REGION
1. LIQUID PHASE
2. ALPHA SOLID SOLUTION PHASE
3. BETA SOLID SOLUTION PHASE
4. ALPHA + LIQUID PHASE
5. BETA + LIQUID PHASE
6. ALPHA + BETA SOLID SOLUTION PHASE (eutectic
point)

14. PHASE DIAGRAM FOR PARTIALLY SOLID
SOLUTION