test 1 Flashcards
How does plastic deformation occur in a metal?
crystalline slip with dislocation motion
An edge dislocation consists of
an extra half plane of atoms
What effect does plastically deforming a metal have on its ductility?
decreases
An interstitial consists of
an extra single atom between normal lattice points
For a metal of a given composition, which would you expect to have the higher strength? A
sample with a fairly low number of dislocations or a sample with a very large number of
dislocations?
a high number
Dislocations remain fixed in a crystalline material during plastic deformation.
False
Interstitial
A point defect with an extra (same
type) atom inserted into the lattice
at the site that is not a lattice site
Frenkel defect
A vacancy-interstitial pair formed
when an ion jumps from a normal
lattice point to an interstitial site.
Schottkey defect
An anion/cation vacancy pair
Edge Dislocation
A crystal defect where there is an
extra half plane of atoms inserted
into the lattice
Grain Boundary
A defect where two grains with
different crystallographic
orientations meet
Plastic Deformation
Permanent deformation as a
response to an applied load
Elastic Deformation
Temporary deformation as a
response to an applied load
Dislocations remain fixed in a crystalline material during plastic deformation.
False
The ways a metal can be strengthened include all except…
High temperature strengthening
What effect does plastically deforming a metal have on its ductility?
decreases
What effect does plastically deforming a metal have on its ductility?
decreases
What do you expect would happen to the yield strength of a high purity metal if you added
atoms of a different type?
the yield strength would increase
In most materials, ductility and strength increase together.
False
For a metal of a given composition, which would you expect to have the higher strength? A
sample with a fairly low number of dislocations or a sample with a very large number of
dislocations?
a high number
Which material type is sensitive to damage from ultraviolet radiation?
Polymers
Metals
usually have some ductility
Ceramics
are brittle
Semiconductors
are brittle
Thermoplastic polymers
usually have some ductility
Thermoset polymers
are brittle
Elastomer polymers
usually have some ductility
Rank Stiffness 1 low 3 high
Ceramic:
Metal:
Thermoplastic:
Thermoset:
3
2
1
1
Which of the following materials is not a ceramic?
Zn
Materials formed from two or more materials (as opposed to elements) that produce unique
properties that are not attainable from one group alone are:
composites
Which material type has the highest stiffness?
ceramics
A polymer that softens when heating (repeatable) is a
thermoplastic
Melting point low1 to high 3 Ceramic: Metal: Thermoplastic Thermoset
3
2
1
1
The composition of a semiconductor can be tailored by very small changes in the
composition
True
The bond type in which valence electrons are not bound to an atom in the solid but drift
around and form a “sea of electrons” is:
metallic
At the equilibrium interatomic spacing, the energy of the solid is minimized.
True
he melting point of lead is 621.5 F while the melting point of alumina (aluminum oxide) is
3762 F. Which would you expect to have a higher bond strength?
Alumina
Would you expect MgO or magnesium to have the higher stiffness?
MgO
The type of bonding that best conducts electricity is
metallic
The major bond type in metals is:
metallic
Metallic bonding consists of
cations surrounded by a sea of electrons that can move around
The atomic spacing of iron is different on different continents.
False
What is the difference between a ceramic and a glass? More than one answer is possible!
Glass is transparent; Ceramic is not
Glass is amorphous; Ceramic is crystalline
The smallest subdivision of a crystalline structure that retains the characteristics of the entire
lattice is called a
unit cell
Are amorphous structures more likely to be found in materials that have complex
molecules/structures or in materials with simple structures?
complex
Match the material to the correct degree of Crystallinity
Metal
Crystalline
Match the material to the correct degree of Crystallinity
Ceramic
Crystalline
Match the material to the correct degree of Crystallinity
Glass
Amorphous
Match the material to the correct degree of Crystallinity
Semiconductor
Crystalline
Match the material to the correct degree of Crystallinity
Thermoplastic Polymer
Mix of Crystalline and amorphous
Match the material to the correct degree of Crystallinity
Thermoset Polymer
Amorphous
Which one of the following terms best describes the structure of a glass?
amorphous
What are Mechanical Properties
Strength
Impact Resistance
Stiffness
Another name for a rubber is
elastomer
Which polymer type has the highest ductility?
Elastomer
typical materials group
Polymers
Metals
Composites
Semiconductors
Ceramics are usually:
compounds of metallic and nonmetallic elements
Certain materials, such as tungsten carbide, are compounds made up of both metallic and
non-metallic elements. To which category of materials does tungsten carbide belong?
ceramics
Characteristics of Ceramic
Poor Electrical and thermal conductor
Excellent high temp resistance
high hardness
Bonding Energy Low to High Melting Temp
CsCl 649
MgO 3932
NaCl 766
3
1
2
Metallic bonding consists of
cations surrounded by a sea of electrons that can move around
Tungsten has a stiffness of 59.2x10 psi. Nickel has a stiffness of 30.0x10 psi. Molybdenum
has a stiffness of 43.4x10 psi. Which would you expect to have the highest melting point?
Tungsten
The bond type in which valence electrons are not bound to an atom in the solid but drift
around and form a “sea of electrons” is:
metallic
At the equilibrium interatomic spacing, the energy of the solid is minimized.
True
Stiffness
Amount something gives in the reg
Creep
Deformation from a load in respect to heat
Fatigue
Failure from cyclic forces
Yield Strength
Maximum Load without permanent deformation
Materials with the exact same composition will have the same properties even if the
processing steps to produce them are different
False
Which material type has the highest density?
metals
Which curve would be for the material with the highest modulus of elasticity?
https://screenshots.firefox.com/KTRqPGEnIbOzfEBD/null
Curve B
Which of the following bond types is the weakest?
van der Waals
Compound A has a bond strength of 25 kcal/mole while compound B has a bond strength of
250 kcal/mole. Which compound would you expect to have the highest stiffness?
Compound B