1. Fundamental concepts of metals science
Properties of metals
Metallic crystal structures
What is crystalline lattice?
Atomic bonding in solids
Lattice parameters
Crystal systems
Polymorphism of metals
Anisotropy
Imperfections in solids

2. Imperfections in solids
Idealized solid and real crystalline solids
What are imperfections in crystal structures?
Classification of crystalline defects
Point defects
Linear defects
Interfacial defects
Volume imperfections
Imperfections and strength of crystalline solids

3. Classification of imperfections in solids

4. Point defects
Self-interstitial

5. Point defects

6. Linear defects
Edge
dislocation

7. Linear defects
Screw
dislocation

8. Linear defects
Mixed dislocation

9. Linear defects Dislocations in titanium alloy (transmission
electron micrograph,
51,450 x)

10. Linear defects Strength depends on the density of dislocations:
1 – idealized crystal,
2 – single crystals,
3 – annealed metals (polycrystalline),
4 – strained metals
Dislocation density ρ is the total dislocation length per unit volume:

11. Interfacial defects
Grain boundaries

12. Interfacial defects The grain boundary acts as a barrier
to dislocation motion

13. Grain boundaries in iron are visible due to the etching
Interfacial defects
Grain boundaries in iron are visible due to the etching

14. Nonmetallic inclusions
Volume, or bulk defects
Nonmetallic inclusions

15. Nonmetallic inclusions
Volume, or bulk defects
Nonmetallic inclusions

16. Nonmetallic inclusions are the sites of crack formation
Volume, or bulk defects
Nonmetallic inclusions are the sites of crack formation

17. Brittle fracture of ship hull
Volume defects
Wrought rivet
Brittle fracture of ship hull
One of the possible reasons is the presence of nonmetallic inclusions in the metal of the hull (or in welded seams, in rivets).

18. Volume defects
At an angle of 22 °, the Titanic's stern broke off from the hull between the third and fourth funnels.