ENGINEERING
MATERIALS
DR. ANEELA WAKEEL

Atomic mass Cu=63.5g/mol

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CRYSTALLINE STRUCTURE
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Axial length are represented by a, b,
c.
Interaxial angles are α, β, γ.

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FCC=12

COORDINATION NUMBER
Number of nearest neighbours or touching atoms
around an atom
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Coordination number
(SC)=6
BCC=8
FCC=12
The primitive, body-centred and face-centred cubic unit cells.mp4

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CRYSTAL STRUCTURE
CHARACTERISTICS
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Determine the density of BCC iron, which has a lattice
parameter of 0.2866 nm.
Example 3.4 SOLUTION
Atoms/cell = 2, a0 = 0.2866 nm = 2.866  10-8 cm
Atomic mass = 55.847 g/mol
Volume of unit cell = = (2.866  10-8 cm)3 = 23.54  10-24
cm3/cell
Avogadro’s number NA = 6.02  1023 atoms/mol
3
0
a
3
23
24
/
882
.
7
)
10
02
.
6
)(
10
54
.
23
(
)
847
.
55
)(
2
(
number)
s
adro'
cell)(Avog
unit
of
(volume
iron)
of
mass
)(atomic
atoms/cell
of
(number
Density
cm
g
=


=
=
−



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MILLER INDICES
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DRAW PLANE FROM MILLER
INDICES
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