Imperfection in solids
By Patama VisuttipitukulE-mail: [email protected]
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Solid
• Solid – State of materials – Rigid – Strong bonding – ionic, van der Waals , metal
bonding – normally has crystal structure
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Examples of Imperfections #1
Imperfection in solid
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Examples of Imperfections #2
distortion of planes
distortion of planes
Imperfection
Imperfection
Imperfection causes distortion of planes and abnormal arrangement of atoms. This affects properties of materials: mechanical, electrical properties and so on.
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Imperfection: Defect causes by an atom #1
This defect called “Vacancy”
Vacancy
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This defect called “SubstitutionalSolid Solution” (by a bigger atom)
Imperfection: Defect causes by an atom #2
Substitutional Solid Solution
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This defect also called “Substitutional Solid Solution”(by a smaller atom)
Imperfection: Defect causes by an atom#3
Substitutional Solid Solution
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This defect also called “Interstitial Solid Solution” (by a very small atom)
Imperfection: Defect causes by an atom#4
Space between atoms
Interstitial Solid Solution
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Imperfection: Defect causes by an atom #5
• Summary: defects cause by an atom could be:– Vacancy– Substitutional solid solution (by bigger or smaller
atoms)– Interstitial solid solution
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Imperfection: Defect causes by an atom #7
• Amount or number of “defect” found in crystal can be calculated by
Number of defect depends on Temperature.
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• Defect causes by an atom has no dimension or zero dimension !!
• It can be called “Point defect” .Remember that point defect is a defect causes by an atom (or
absence of atom) and it has zero dimension.
• There are other kinds of defects which have one, two or three dimensions (1D, 2D, 3D).
Note that :1D has only length (L)2D has length (L)*width(W)3D has length(L)*width(W)*depth(D)
Imperfection: Defect causes by an atom #8
LL
W
LW
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• Defect causes by an atom has no dimension or zero dimension !!
• It can be called “Point defect” .Remember that point defect is a defect causes by an atom (or
absence of atom) and it has zero dimension.
• There are other kinds of defects which have one, two or three dimensions (1D, 2D, 3D).
Note that :
1D has only length (L)2D has length (L)*width(W)3D has length(L)*width(W)*depth(D)
LL
W
LW
D
Imperfection: Line Defect
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Imperfection- Line defect #1
This type of dislocation is called “Edge dislocation” which can be considered as a line defect.
Perfect crystal
Perfect crystal
Extra plane
Line defect or
‘Dislocation’
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Imperfection- Line defect #2
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Imperfection- Line defect #3
The “Screw dislocation” also can be considered as a line defect in materials
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• Defect causes by an atom has no dimension or zero dimension !!
• It can be called “Point defect” .Remember that point defect is a defect causes by an atom (or
absence of atom) and it has zero dimension.
• There are other kinds of defects which have one, two or three dimensions (1D, 2D, 3D).
Note that :1D has only length (L)
2D has length (L)*width(W)3D has length(L)*width(W)*depth(D)
LL
W
LW
D
Imperfection: Interfacial Defect
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Imperfection- Interfacial defect #1
Atom “A”
Atom “B”
Planar
DefectPlanar
Defect
“Planar defect” or “Interfacial defect” is a two-dimensions defect such as interface between two materials, grain boundary and so on.
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Imperfection- Interfacial defect #2
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• Defect causes by an atom has no dimension or zero dimension !!
• It can be called “Point defect” .Remember that point defect is a defect causes by an atom (or
absence of atom) and it has zero dimension.
• There are other kinds of defects which have one, two or three dimensions (1D, 2D, 3D).
Note that :1D has only length (L)2D has length (L)*width(W)
3D has length(L)*width(W)*depth(D)
LL
W
LW
D
Imperfection: Bulk Defect
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Imperfection- Bulk defect #1
Perfect crystal
Imperfection or “Defect” occurs
Defect is a three-dimensions defect (it has height, width and length).
Bulk defects can be impurities, hole, crack … which have three-dimensions.
H
W L
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Summary about imperfections
• Crack, Holes, Impurities Bulk defects
Interfacial defects
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Dislocation VS Mechanical properties #1
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Dislocation VS Mechanical properties #2
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Dislocation VS Mechanical properties #3
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Dislocation VS Mechanical properties #4
Slip occurs in these plane
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Dislocation VS Mechanical properties #5
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Dislocation VS Mechanical properties #6
Need low
force
Need higher force
Low dislocation density Deform easily High dislocation density Deform hardly
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Dislocation VS Mechanical properties #7
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Summary of Dislocation VS Mechanical properties
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Calculation of concentration
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• Other useful relationsCalculation of concentration
3
2
2
1
1
11 10" ×
⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜
⎝
⎛
+=
ρρCC
CC 3
2
2
1
1
21 10" ×
⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜
⎝
⎛
+=
ρρCC
CC
2
2
1
1
100
ρρ
ρ CCave
+=
2
22
1
11
2211
''''
ρρ
ρ ACACACAC
ave
+
+=
2
2
1
1
100
AC
ACAave
+=
100'' 2211 ACACAave
+=
Concentration in mass per unit volume (kg/m3)
Average density (kg/m3)
Average atomic weight
Note that: 1. these equations can be used for two element alloy.
2. C is concentration by weight (weight percent), C’ is concentration by atom(atomic percent).Imperfection in Solids by Patama Visuttipitukul
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Example in concentration calculation
• Al 94 g+ Cu 6 g– Calculate weight percent of Al and Cu– Calculate atomic percent of Al and Cu– Calculate concentration by mass per unit
volume– Calculate average density– Calculate average atomic weight