1. Grain in Metals

2. Grains and Grain-Boundaries

3. Regular arrangement of atoms in solids

4. 3-dimensional lattice

5. BCC (iron) Crystal lattice

6. In real crystals, spherical atoms are in contact with each other

7. BCC and FCC Lattices

8. Alloys
When 2 metals are melted together, then upon solidification, they may exhibit any of the following:
Unlimited solid solubility
No solid solubility
Partial solid solubility
Formation of ‘intermetallic compounds’

9. Solid Solution Lattice

10. Intermetallic compound

11. 2nd phase precipitates

15. Allotropy
Some elements exhibit more than one crystal structures. This phenomenon is called Allotropy
e.g., IRON exists in:
upto 912°C BCC (body centered cubic)
912°C °C FCC (face centered cubic)
1394°C – melting BCC

16. Two crystallographic form of Carbon

17. Allotropes of Uranium
alpha (orthorhombic) Uranium Stable up to 667.7°C
beta (tetragonal) Uranium Stable ° °C
gamma (body-centered cubic) Uranium Stable 774.8°C - melting point This is the most malleable and ductile state.

18. Iron-Iron Carbide Diagram

19. Steel portion of Fe-C dagram