TEST 1

Question 1

Mark each of the following terms that represent a typical materials group. (Note: all groups may not be listed.)

a) Metals
b) Concrete
c) Semiconductors
d) Woven Materials
e) Polymers
f) Composites

Answer 1

Metals
Semiconductors
Polymers
Composites

Question 2

Which one of the following statements is not a typical characteristic for a metal?

a) high strength and stiffness
b) lustrous
c) good electrical and thermal conductivity
d) brittle
e) crystalline

Answer 2

Brittle

Question 3

The bond type in diamond is:

a) ionic
b) metallic
c) covalent
d) secondary

Answer 3

covalent

Question 4

The major bond type in metals is:

a) ionic
b) metallic
c) covalent
d) secondary

Answer 4

metallic

Question 5

Ceramics are usually:

a) compounds of metallic and nonmetallic elements
b) made up of two different metallic elements
c) a combination of two or more material types with one serving as a reinforcement
d) made up of long, chain-like molecules

Answer 5

compounds of metallic and nonmetallic elements

Question 6

Which one of the following statements is not a typical characteristic for a
ceramic?
a) good ductility and formability
b) poor electrical and thermal conductivity
c) excellent high temperature resistance
d) high hardness

Answer 6

good ductility and formability

Question 7

Which of the following materials is not a ceramic?

a) Al2O3
b) Zn
c) MgO
d) SiO2
e) WC

Answer 7

Zn

Question 8

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:

a) covalent
b) ionic
c) metallic
d) van der Waals

Answer 8

metallic

Question 9

The bond type in which electrons are shared between adjacent atoms to form a stable group of 8 electrons is:

a) metallic
b) ionic
c) covalent
d) van der Waals

Answer 9

covalent

Question 10

A polymer that softens when heated but becomes brittle when cooled is

a) thermoplastic
b) thermosetting

Answer 10

thermoplastic

Question 11

Materials formed from two or more materials (as opposed to elements) that produce unique properties that are not attainable from one group alone are:

a) metals
b) ceramics
c) composites
d) polymers
e) semiconductors

Answer 11

composites

Question 12

Some of the more expensive golf clubs use “graphite shafts”. What does this really mean?

a) the shaft is solid, high-strength carbon
b) the shaft is a carbon matrix, carbon fiber reinforced material
c) the shaft is a polymer matrix, carbon fiber reinforced material
d) the shaft is a carbon matrix, glass fiber reinforced material
e) the shaft is a polymer matrix, carbon aggregate reinforced material

Answer 12

the shaft is a polymer matrix, carbon fiber reinforced material

Question 13

A material that exhibits only short range order is called

a) crystalline
b) ionic
c) amorphous
d) irregular
e) covalent

Answer 13

amorphous

Question 14

The smallest subdivision of a crystalline structure that retains the characteristics of the entire lattice is called a

a) lattice point
b) lattice parameter
c) crystal
d) lattice plane
e) unit cell

Answer 14

unit cell

Question 15

Are amorphous structures more likely to be found in materials that have complex molecules/structures or in materials with simple structures?

a) complex
b) simple

Answer 15

complex

Question 16

Which one of the following terms best describes the structure of a glass?

a) single crystal
b) amorphous
c) polycrystalline
d) polymeric

Answer 16

amorphous

Question 17

Do amorphous materials have grain boundaries?

a) yes
b) no

Answer 17

no

Question 18

A vacancy consists of

a) an extra atom between normal lattice points
b) a missing plane
c) an extra plane in a crystal
d) a missing atom on a lattice site
e) an extra half-plane of atoms

Answer 18

a missing atom on a lattice site

Question 19

Calculate the number of vacancies expected in one cubic centimeter of aluminum at 550°C. The activation energy for vacancy formation is 16,890 cal/mol. Aluminum contains 6.02 x 1022 atoms/cm3. Please show your work and mark the appropriate answer.

a) 5.10 x 1021
b) 1.50 x 1021
c) 1.17 x 1016
d) 1.97 x 1018
e) 6.02 x 1019

Answer 19

1.97x10^18

Question 20

An interstitial consists of

a) an extra single atom between normal lattice points
b) a missing plane
c) an extra plane in a crystal
d) a missing atom on a lattice site
e) an extra half-plane of atoms

Answer 20

an extra single atom between normal lattice points

Question 21

An edge dislocation consists of

a) a spiral stacking of crystal planes around the dislocation line
b) a change in stacking sequence
c) an extra half plane of atoms
d) an extra single atom between normal lattice points

Answer 21

an extra half plane atom

Question 22

Do dislocations move or remain fixed in a material during deformation?

a) remain fixed
b) move

Answer 22

move

Question 23

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) a high number
b) a low number

Answer 23

a high number

Question 24

What do you expect would happen to the yield strength of a high purity metal if you added atoms of a different type?

a) The yield strength would decrease
b) The yield strength would increase
c) There would be no change

Answer 24

the yield strength would increase

Question 25

What is the Hall-Petch relationship for?

a) relates grain size in a metal to yield strength
b) relates number of dislocations in a metal to yield strength
c) relates vacancy concentration to density
d) relates interstitial concentration to yield strength

Answer 25

relates grain size in a metal to yield strength