1. Chapter 5 - Imperfections in Solids
Point Defects
Metals
Ceramics
Impurities
Composition Calculations
Dislocations
Interfacial Defects

2. Chapter 5 (continued) Qualitative Questions
23 Describe the different kinds of point defects that exist in
solids. Include the specific differences that exist in
ceramic crystal structures.
24 Define the term solution. Describe the two kinds of solid
solutions and the kinds of atoms that are involved in each.
25 Describe edge and screw dislocations. Include the
appearance of the dislocation and the orientation of the
distortion relative to the dislocation.
Quantitative Questions
6 Be able to convert atomic percent to weight percent and vice-versa

3. Chapter 5 (continued) Introduction
Solids are never _______________________________.
Many properties are ____________________________.
Often the imperfections are _______________________
_________.
A defect is defined as anything that _________________
_______________ of the solid.

4. Chapter 5 (continued)
Defects are usually classified by their dimensionality
__________________ (vacancies, interstitialcies,
impurities, etc)
__________________ (dislocations)
__________________ (surfaces, grain boundary, phase
boundaries, etc)

5. Chapter 5 (continued) Point Defects
There are several types of point defects
___________ definition - a ________________
rarely more than _____________ atoms missing
there is a tendency for vacancies to cluster
vacancies can move
This is caused by atomic movement

6. Chapter 5 (continued)
Figure 5.1

7. Chapter 5 (continued)
The concentration of vacancies ( #/volume) is a function of temperature
where Nv = the number of vacancies / volume
N = the total number of atomic sites
Qv = the energy required to form a vacancy
k = the Boltzmann constant
= 1.38x10-23 J/(atom K)
T = the absolute temperature

8. Chapter 5 (continued) Point Defects (cont.)
___________ - ___________________________________
could be a ________________, but not common due to the stress involved
(This topic will return in the impurity section)

9. Chapter 5 (continued) Point Defects in Ceramics
Both vacancies and interstitialcies are possible. Anion interstitialcies are rare.
_________________ must be maintained
_____________________________

10. Chapter 5 (continued)
Point Defects in Ceramics (cont.)
Figure 5.2

11. Chapter 5 (continued) Point Defects in Ceramics (cont.)
Ceramic point defects can categorized based on the _______________________________
___________ ______ - the species ______ given by the
______________ is maintained
with the defects
_____________________ - a deviation from the
formula ratio is needed to
________________

12. Chapter 5 (continued) Point Defects in Ceramics (cont.)
ex. - if (2) Fe+3 replace (2) Fe+2 another Fe+2 must be removed
Figure 5.4

13. Chapter 5 (continued) Impurities in Solids
There are always _____________ in any metallic crystal
These can show up as point defects
Most familiar metals are ________. The impurity atoms are added ______________.
This ______________________. For example, improved mechanical strength and corrosion resistance

14. Chapter 5 (continued) Impurities in Solids (cont)
Alloys can have two _________________________ (multiphase), or be a ______________________.
Definitions
______ - the element or compound present in the
____________ (the base lattice structure)
__________ amount (the "impurity")

15. Chapter 5 (continued) Impurities in Solids (cont) Definitions (cont)
_____ - a _______________________ of a material with
____________________________________
_____________ - two or more elements ____________
_____________________________
__________________________________________________________________________________________
There are 2 types of solid solutions - ______________ ___________

16. Chapter 5 (continued)
Impurities in Solids (cont.)
Figure 5.5

17. Chapter 5 (continued) Substitutional Solid Solution
solute atoms ___________ for solvent atoms in the lattice
The solvent crystal structure is ______________________
The fraction of substitution can range from 0 to 100%

18. Chapter 5 (continued) Substitutional Solid Solution (cont.)
For ________________________. (In order of importance)
______________ must not differ by more than 15%
__________________________ must be the same
small difference in ___________________
____________. More solubility of solute if it has a higher valence than the solvent
( see front cover for copper / nickel )

19. Chapter 5 (continued) Interstitial Solid Solutions
The solute atoms ________________________ (spaces) in the lattice
Occurs when one atom is much larger than the other
( typically occurs with ____________ )
Even small atoms (except for H) are ________________ ______________ .
Therefore, the ___________________________ (< 10%)
(ex. - about 2% for C in Fe)

20. Chapter 5 (continued) Impurities in Ceramics
Either substitutional or interstitial impurities are possible
Remember _______________. All interstitial impurities and some substitution impurities require a ____________. Substitutions of the same charge do not require another change.
If not another change must be made, it could be a __________________________________________

21. Chapter 5 (continued) Impurities in Ceramics (cont.)
Example Problem 5.2
Assume a Ca+2 substitutes for an Na+1 in an NaCl structure
Possible second changes:
_________________________________

22. Chapter 5 (continued) Composition Conversion
I don’t like the presentation in the book. This is more general.
_____________________________________________________________________________________
Procedure
choose a basis of what you know
use the atomic weight to change to the desired basis
calculate percentages in new basis

23. Chapter 5 (continued) Composition Conversion (cont.)
example mole percent to weight percent
An alloy consists of 20 mole % Cu, 30 mole % Sn and
50 mole % Pb. What is the composition on a weight
percent basis?
assume 100 moles total
convert to mass units
calculate weight percents

24. Chapter 5 (continued) Composition Conversion (cont.)
20 mole Cu * 63.5 g/mole = g Cu
30 mole Sn * g/mole = g Sn
50 mole Pb * g/mole = g Pb
15191 g total
1270 / = g Cu / g tot or wt % Cu
3561 / = g Sn / g tot or wt % Sn
10360 / = g Pb / g tot or wt % Pb

25. Chapter 5 (continued) Composition Conversion (cont.)
example weight percent to mole percent
A mixture consists of 10 wt % hydrogen (H),
30 wt % nitrogen (N), and 60 wt % chlorine (Cl).
What is the composition on a mole percent basis?
assume 100 grams total
convert to mole units
calculate mole percents

26. Chapter 5 (continued) Composition Conversion (cont.)
10 g H / g/mole = mole H
30 g N / 14 g/mole = mole N
60 g Cl / g/mole = mole Cl
13.75 mole total
9.92 / = mol H / mol tot or mol % H
2.14 / = mol N / mol tot or mol % N
1.69 / = mol Cl / mol tot or mol % Cl

27. Chapter 5 (continued) Linear Defects - (aka Dislocations)
A _________________ defect around which the ________ ______________ .
There are two types of dislocations, plus combinations
________________

28. Chapter 5 (continued) Linear Defects (cont.) Edge dislocation
A _______________ which terminates within the crystal.
There is _______________________________________. Compression on one side, tension on the other.
The distortion is _______________ to the dislocation line.

29. Chapter 5 (continued)
Edge dislocation (cont.)
Figure 5.7

30. Chapter 5 (continued) Linear Defects (cont.) Screw dislocation
Caused by a ______________. A portion of the crystal is shifted by one atom.
Looks like a _____________.
The distortion is ___________ to the dislocation line

31. Chapter 5 (continued)
Figure 5.8
Screw dislocation

32. Chapter 5 (continued) Linear Defects (cont.) Mixed Dislocation
Often dislocations
show features of
both
Figure 5.9

33. Chapter 5 (continued) Interfacial Defects ________________defects.
Anything that deviates from perfect crystal packing
_____________________________________________
External surfaces
The external atoms are not surrounded by all possible nearest neighbors, therefore they are at a higher energy.

34. Chapter 5 (continued) Interfacial Defects (cont) Grain boundaries
There is an ________________ where the grains meet
These can be low angle or high angle
The atoms are less tightly packed, __________________ ___________________ .
Grain boundaries are more chemically reactive

35. Chapter 5 (continued)
Interfacial Defects (cont)
Figure 5.11

36. Chapter 5 (continued) Interfacial Defects (cont) Tilt Boundaries
________________ can
_______ themselves.
This extends the defect
into a second dimension.
Figure 5.12

37. Chapter 5 (continued) Interfacial Defects (cont) Twin Boundaries
A __________ lattice
symmetry
Occurs along specific
crystal planes.
Figure 5.13

38. Chapter 5 (continued) Interfacial Defects (cont)
Miscellaneous interfacial defects
_______ faults from a break in the _______ pattern in FCC crystals or __________ pattern in HCP crystals
Phase boundaries (see Chapter 10)