Materials Technology Structure of Materials
Post on 12-Feb-2016
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Materials Technology
Structure of Materials
Structure of Materials• All materials are composed of atoms
Structure of Materials
The hydrogen atom
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.
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 eyeMagnified view – Large grains on sheet metal cause a rough surface
Structure of MaterialsInternal structure of typical
thermoplastic materials.
Aligned Molecules Branched Molecules
Aligned Molecules Branched Molecules
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
Structure of Materials
Internal structure of typical thermosetting plastics.
Cross-linked molecular chains
A cross-linked structure has adjacent chains linked by strong primary covalent bonds
Structure of MaterialsThe Body Centred Cubic Structure
BCC
Structure of MaterialsThe Face Centred Cubic Structure
FCC
Structure of Materials
Internal structure of typical hardwood
Structure of Materials
Internal structure of typical softwood
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