test 1 Flashcards by jadarius armstead

How does plastic deformation occur in a metal?

crystalline slip with dislocation motion

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An edge dislocation consists of

an extra half plane of atoms

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What effect does plastically deforming a metal have on its ductility?

decreases

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An interstitial consists of

an extra single atom between normal lattice points

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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

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Dislocations remain fixed in a crystalline material during plastic deformation.

False

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Interstitial

A point defect with an extra (same
type) atom inserted into the lattice
at the site that is not a lattice site

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Frenkel defect

A vacancy-interstitial pair formed
when an ion jumps from a normal
lattice point to an interstitial site.

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Schottkey defect

An anion/cation vacancy pair

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Edge Dislocation

A crystal defect where there is an
extra half plane of atoms inserted
into the lattice

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Grain Boundary

A defect where two grains with
different crystallographic
orientations meet

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Plastic Deformation

Permanent deformation as a

response to an applied load

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Elastic Deformation

Temporary deformation as a

response to an applied load

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Dislocations remain fixed in a crystalline material during plastic deformation.

False

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The ways a metal can be strengthened include all except…

High temperature strengthening

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What effect does plastically deforming a metal have on its ductility?

decreases

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What effect does plastically deforming a metal have on its ductility?

decreases

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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

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In most materials, ductility and strength increase together.

False

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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

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Which material type is sensitive to damage from ultraviolet radiation?

Polymers

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Metals

usually have some ductility

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Ceramics

are brittle

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Semiconductors

are brittle

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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?

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