Materials Technology

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• Materials Technology
• Structure of Materials

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Structure of Materials

• Structure of Materials
• All materials are composed of atoms

The hydrogen atom
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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.

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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.

The crystals begin to form independently at
random locations
Crystals continue to grow as solidification
continues
Note that the orientation of each site is
different
Fully solidified metal showing individual grains
and grain boundaries
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
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Structure of Materials

• Internal structure of typical thermoplastic
  materials.

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

• The Body Centred Cubic Structure
• BCC

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Structure of Materials

• The Face Centred Cubic Structure
• FCC

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Structure of Materials

• Internal structure of typical hardwood

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Structure of Materials

• Internal structure of typical softwood