1. Structure of Materials
Materials Technology
Structure of Materials

2. Structure of Materials
All materials are composed of atoms
The hydrogen atom

3. Structure of Materials
The arrangement of atoms within a material greatly influences that materials behaviour and properties e.g.
Hardness
Ductility
Malleability
Conductivity
Melting point, etc.

4. Structure of Materials
When metals solidify from a molten state the atoms configure themselves in an orderly arrangement called crystals. When formed this is called the crystalline (lattice) structure.
The smallest group of atoms showing this lattice structure is called the unit cell.
Note that the orientation of each site is different
Fully solidified metal showing individual grains and grain boundaries
Crystals continue to grow as solidification continues
The crystals begin to form independently at random locations
The grains of zinc on the surface of galvanized steel are visible to the naked eye
Magnified view – Large grains on sheet metal cause a rough surface

5. Structure of Materials
Internal structure of typical thermoplastic materials.
Adjacent chains are held together by weak Van der Waals forces
During polymerisation the monomers are linked together by strong primary covalent bonds (sharing electrons)
Aligned Molecules
Branched Molecules
Aligned Molecules
Branched Molecules

6. Structure of Materials
Internal structure of typical thermosetting plastics.
A cross-linked structure has adjacent chains linked by strong primary covalent bonds
Cross-linked molecular chains

7. Structure of Materials
The Body Centred Cubic Structure
BCC

8. Structure of Materials
The Face Centred Cubic Structure
FCC

9. Structure of Materials
Internal structure of typical hardwood

10. Structure of Materials
Internal structure of typical softwood