Structure and manufacturing Properties of Metals

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Chapter 3
Structure and manufacturing Properties of Metals

• Crystal structure of metals
• Role of various imperfections
• Importance of grain
• Failure and fracture of metals
• Ferrous and non-ferrous metals, alloys

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Covalent Bond

• Some Common Features of Materials with Covalent
  Bonds
• Hard
• Good insulators
• Transparent
• Brittle or cleave rather than deform

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Metallic bond

• Some Common Features of Materials with Metallic
  Bonds
• Good electrical and thermal conductors due to
  their free valence electrons
• Opaque
• Relatively ductile

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Ionic Bond

• Some Common Features of Materials with Ionic
  Bonds
• Hard
• Good insulators
• Transparent
• Brittle or cleave rather than deform

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Body-Centered Cubic (BCC) Structure
Face Centered Cubic (FCC) Structure
Hexagonal Close Packed (HPC) Structure
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the atoms in rows A and C are no longer aligned
cubic lattice structures allow slippage to occur
more easily than non-cubic lattices, so hcp
metals are not as ductile as the fcc metals.
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1. Interstitial impurity atom
2. Edge dislocation
3. Self interstitial atom
4. Vacancy
5. Precipitate of impurity atoms
6. Vacancy type dislocation loop
7. Interstitial type dislocation loop
8. Substitutional impurity atom

Defect
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a dislocation is a crystallographic defect, or
irregularity, within a crystal structure
Simple Cubic Lattice showing atomic planes
(marked in red)
Screw dislocation
Edge dislocation
Burgers vector in black, dislocation line in blue.
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Edge Dislocation
Screw Dislocation
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Grain
a) Nucleation of crystals b) crystal growth c)
irregular grains form as crystals grow together
d) grain boundaries as seen in a microscope
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Atoms along the boundary
packed less efficiently
Grain Boundary
more disordered
Polycrystalline Deformation
before
after
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