Table of Contents
Get All Weeks Materials Science: 10 Things Every Engineer Should Know Quiz
Quiz 01: Thing 1
Q1. The first three categories introduced in this segment (metals, polymers, and ceramics) are based on the three types of primary bonding: metallic, ________, and ionic, respectively.
secondary
van der Waals
covalentQ2. Glasses are considered a category separate from ceramics because their chemistry is different, even though their atomic structure is the same.
True
FalseQ3. Fiberglass is a good example of a ___________ combining the strength and stiffness of reinforcing glass fibers with the ductility of the polymeric matrix.
ceramic
composite
semiconductorQ4. Semiconductors are considered a category separate from metals because their electrical conductivity is different.
True
FalseQ5. The relationship between atomic bonding and the elastic modulus or stiffness of a metal is an example of how structure (atomic level in this case) leads to _____________.
permanent deformation
properties
breakageQuiz 02: Thing 2
Q1. Aluminum metal is an example of a ______________.
simple cubic crystal structure
body-centered cubic crystal structure
face-centered cubic crystal structureQ2. The vacancy and the interstitial are two common types of point defects in metallic crystal structures.
True
FalseQ3. The Arrhenius relationship shows that the rate of chemical reactions increases _______________ temperature.
linearly with
exponentially with
the fourth power ofQ4. The Arrhenius plot is a linear set of data points in which the logarithm of the rate is plotted against the ____________.
the absolute temperature in K
inverse temperature in K-1
temperature in °CQ5. The activation energy, Q, for a chemical reaction is indicated by the _______________ of the Arrhenius plot.
slope
intercept at 1/T = 0
intercept at 1/T = 1Q6. The gas constant, R, is equal to _______________ times Boltzmann’s constant, k.
1024
Avogadro's number
10-24Q7. The gas constant, R, is an appropriate term for equations describing gas phases and ________________ processes.
solid-state
no other
all otherQ8. The energy needed to produce a single vacancy, Ev, is the same as the activation energy,
True
FalseQ9. Solid-state diffusion occurs in the face-centered cubic structure of aluminum by individual aluminum atoms hopping into _______________ sites.
adjacent occupied
adjacent interstitial
adjacent vacantQ10. As an indication of how “close-packed” the aluminum (FCC) crystal structure is, ________ of the volume of the unit cell is occupied by the aluminum atoms.
74%
70%
68%Q11. The diffusion coefficient is defined by _______________.
Fick’s second law
Fick’s first law
Fick’s third lawQ12. The diffusivity (D) of copper in a brass alloy is 10-20 m2/s at 400 °C. The activation energy for copper diffusion in this system is 195 kJ/mol. The diffusivity at 600 °C is _____________.
2.93 x 10-16 m2/s
5.86 x 10-17 m2/s
2.93 x 10-17 m2/sQuiz 01: Thing 3
Q1. An edge dislocation corresponds to an extra ______________.
full plane of atoms
cluster of atoms
half-plane of atomsQ2. An edge dislocation is a linear defect with the Burgers vector _______________ to the dislocation line.
at a 45-degree angle
perpendicular
parallelQ3. Crushing an empty soda can made of aluminum alloy is an example of ______________.
viscous deformation
plastic deformation
elastic deformationQ4. Plastic deformation by dislocation motion is a ___________ alternative to deforming a defect-free crystal structure.
high-stress
low-stress
stress-freeQuiz 02: Thing 4
Q1. The first of the “big four” mechanical properties obtained in the tensile test is ___________________.
yield strength
elastic modulus
tensile strengthQ2. The tensile strength is ___________ the yield strength for typical metal alloys.
greater than
about the same as
less thanQ3. The ductility corresponds to the ______________.
strength at failure
total amount of elastic deformation
strain at failureQ4. The Elastic Modulus is given by ______________.
Hooke’s Law
Poisson’s ratio
Ohm’s LawQ5. The yield strength corresponds to ______________.
an offset of 0.2%
an offset of 0.1%
the point of tangency where plastic deformation first beginsQ6. The stress versus strain curve shows that a metal alloy becomes weaker beyond the tensile strength.
True
FalseQ8. The elastic “snap back” that occurs at failure is parallel to ______________.
the stress axis
the elastic deformation portion of the stress-strain curve.
the strain axisQ9. The Toughness or work-to-fracture is the total area under the stress versus strain curve.
True
FalseQuiz 01: Thing 5
Q1. “Creep” deformation describes the behavior of materials being used at high temperatures under high pressures over _____________ time periods.
long
intermediate
shortQ2. We added comments about polymers because their weak, secondary bonding between long-chain molecules causes them to exhibit creep deformation at relatively low temperatures.
True
FalseQ3. In the simplest sense, the creep test is essentially a tensile test done at a high temperature under ____________ load.
a fixed
no
a variableQ4. A linear portion of the strain versus time plot corresponds to the ______________ stage of the overall creep curve.
secondary
tertiary
primaryQ5. The strain rate in the ______________ stage of the creep test is analyzed using the Arrhenius equation, analogous to our previous discussion of the diffusion coefficient.
secondary
primary
tertiaryQ6. A powerful use of the Arrhenius relationship is to measure creep data at low temperatures and then extrapolate the data to high temperatures, allowing us to predict the performance there.
True
FalseQ7. In a laboratory creep experiment at 1,000 °C, a steady-state creep rate of 5 x 10-1 % per hour is obtained for a metal alloy. The activation for creep in this system is known to be 200 kJ/mol. We can then predict that the creep rate at a service temperature of 600 °C will be ______________. (We can assume the stress on the sample in the laboratory experiment is the same as at the service temperature.)
80.5 x 106 % per hour
4.34 x 10-5 % per hour
8.68 x 10-5 % per hourQ8. For high-temperature creep deformation in ceramic materials, a common mechanism is ______________.
dislocation climb
viscous flow (molecules sliding past one another)
grain boundary slidingQuiz 02: Thing 6
Q1. The ductile-to-brittle transition was first discovered in conjunction with the failure of ______________
the Queen Mary
the Titanic
Liberty ShipsQ2. The impact energy is an indicator of whether a fracture is ductile or brittle, as measured by the ____________ test
creep
tensile
CharpyQ3. Although they have equally high atomic packing densities, face-centered cubic (fcc) metals with more slip systems are typically ductile while hexagonal close-packed (hcp) metals are relatively __________.
strong
weak
brittleQ4. Body-centered cubic (bcc) alloys such as low-carbon steels demonstrate the ductile-to-brittle transition because their dislocation motion tends to be ___________ than that in the more densely packed fcc alloys.
more erratic
slower
fasterQuiz 01: Thing 7
Q1. We focus on “critical flaws” that ______________.
are larger than 1 mm in size
lead to catastrophic failure
are larger than 1 μm in sizeQ2. We use the example of __________________ to illustrate concern about a famous “critical flaw.
Liberty Ships
the Hindenburg
the Liberty BellQ3. The design plot is composed of two intersecting segments: yield strength corresponding to general yielding and fracture toughness corresponding to ______________
fracture following multiple stress applications
high-temperature fracture
flaw-induced fractureQ4. The design plot shows stress as a function of time.
True
FalseQ5. The ______________ flaw size is defined within the design plot at the intersection between the general yielding segment and the flaw-induced fracture segment
critical
minimum
maximumQ6. The I in the subscript of the fracture toughness, KIc , refers to ______________.
mode I (uniaxial tensile) loading
“i” for incremental loading
the primary stage of creep deformationQ7. The stress versus strain curve for a sample with a critical pre-existing flaw looks like ______________.
regular stress versus strain curve but with a lower value of Y.S.
regular stress versus strain curve but with a higher value of Y.S.
that of a brittle ceramicQ8. The benefit of failure by general yielding is that ______________.
the plastic deformation serves as an early warning
the structure does not deform permanently
the failure occurs quicklyQ9. “Flaw-induced fracture” is also known as “catastrophic fast fracture.”
True
FalseQuiz 02: Thing 8
Q1. The fatigue strength that is associated with catastrophic failure after a large number of stress cycles is ______________ the yield strength.
greater than
less than
about the same value asQ2. A metal alloy known to have good ductility is used in the manufacture of a spring in a garage door assembly. The spring breaks catastrophically in its first use, under a load known to correspond to about 2/3 of the alloy’s yield strength. This is a good example of fatigue failure.
True
FalseQ3. The fatigue curve is a plot of breaking stress versus ______________.
temperature
time
the number of stress cyclesQ4. The “fatigue strength” is defined as the point where the fatigue curve reaches a value of roughly _____________ of the tensile strength.
75%
10%
one-fourth to one-halfQ5. Fatigue is the result of a critical flaw built up ______________
prior to being put into service
instantly
after a large number of stress cyclesQ6. The relationship of fatigue to the design plot (introduced in our discussion of fracture toughness) is that we grow the size of a flaw at relatively low stress until the flaw size reaches the “flaw-induced fracture” segment of the design plot.
True
FalseQuiz 01: Thing 9
Q1. We begin by focusing on making things slowly. Phase diagrams are maps that help us track microstructural development during the slow cooling of an alloy. The Sn-Bi phase diagram is an example of a ______________ diagram.
temperature versus time
eutectoid
eutecticQ2. The phases in a two-phase region of the phase diagram are determined by the adjacent, single phases on either side of that two-phase region
True
FalseQ3. In the important Fe – Fe3C (iron carbide) phase diagram, steelmaking is described by slow cooling through the ______________ reaction
eutectic
melting
eutectoidQ4. The “pasty” quality of lead solders in the lead-tin system can be attributed to ______________.
the nature of the two-phase liquid + α solid solution region
the nature of the two-phase α solid solution + β solid solution region
the fact that lead has a higher melting point than tinQ5. Heat treatment can be defined as the time-independent process of producing a desired microstructure.
True
FalseQ6. Previously (in Thing 2), we saw that diffusion increases as temperature increases. Instability ______________ as temperature decreases.
increases
decrease
stays about the sameQ7. Because of the competition between instability and diffusion, the most rapid transformation will occur _______________.
at the transformation temperature
below the transformation temperature
above the transformation temperatureQ8. The “knee-shaped” curve of the TTT diagram for eutectoid steel is a good example of the competition between instability and ______________.
stability
diffusion
radioactivityQ9. As we monitor the TTT diagram for eutectoid steel through the diffusional transformation region, we see that the decreasing magnitude of diffusivity with decreasing temperature leads to ______________.
increasingly more coarse microstructures
increasingly finer microstructures
generally unchanged grain sizesQ10. As we continue to go to lower temperatures in the TTT diagram for eutectoid steel, the diffusionless transformation to form martensite is the result of ______________.
the domination of instability
increasingly rapid atomic mobility
freezing temperaturesQuiz 02: Ten Things Final
Q1. The first three categories introduced in the opening of the course (metals, polymers, and ceramics) are based on the three types of primary bonding: metallic, covalent, and ____________, respectively.
ionic
hydrogen
van der WaalsQ2. In illustrating the relationship between atomic structure and the elastic modulus or stiffness of a metal (structure leads to properties!), we saw how elastic deformation follows from the stretching of atomic ___________.
bonds
weight
energyQ3. The _________ plot is a linear set of data points in which the logarithm of rate is plotted against the inverse of absolute temperature in K-1.
TTT
fatigue
ArrheniusQ4. In the face-centered cubic structure of aluminum, solid-state diffusion occurs by individual aluminum atoms hopping into adjacent interstitial sites
True
FalseQ5. ___________________ is a linear defect with the Burgers vector perpendicular to the dislocation line.
An interstitial
A vacancy
An edge dislocationQ6. Consider the body of an automobile made of steel. A small dent in that structure, when the automobile is accidentally driven into a barrier, is an example of _________ deformation.
viscous
elastic
plasticQ7. In the tensile test, the yield strength (Y.S.) is found just beyond the linear elastic region (which gives the elastic modulus, E) at an offset of 0.2% strain.
True
FalseQ8. Beyond the tensile strength (T.S.), the maximum stress value measured over the range of the tensile test, we measure the ductility corresponding to the total amount of ______________ deformation.
elastic + plastic
elastic
plasticQ9. For high-temperature creep deformation in metal alloys, a common mechanism that we illustrated is ______________.
dislocation climb
viscous flow (molecules sliding past one another)
grain boundary slidingQ10. A powerful use of the Arrhenius relationship is to measure creep data at high temperatures over conveniently short time periods and then extrapolate the data to __________ temperatures, allowing us to predict the performance of the material over long operating times.
even higher
cryogenic
lowQ11. The impact energy is the standard property for monitoring the ductile-to-brittle transition. The impact energy is commonly measured by means of the ______________.
creep test
Charpy test
tensile tesQ12. Body-centered cubic (bcc) alloys tend to exhibit the ductile-to-brittle transition because they have fewer slip systems than in the ductile face-centered cubic (fcc) alloys.
True
FalseQ13. The design plot is composed of two intersecting segments: yield strength corresponding to ___________ and fracture toughness corresponding to flaw-induced fracture.
high-temperature fracture
general yielding
fracture following multiple stress applicationsQ14. The design plot monitors stress as a function of ______________.
flaw size, a.
strain
timeQ15. A metal alloy known to have good ductility is used in the manufacture of a spring in a garage door assembly. The spring breaks catastrophically after 10 years of regular use, under a load known to correspond to about one-half of the alloy’s yield strength. This is a good example of fatigue failure.
True
FalseQ16. The relationship of fatigue to the design plot (introduced in our discussion of fracture toughness) is that we grow the size of a flaw at relatively low stress until the flaw size reaches the ______________ segment of the design plot.
yield stress
general yielding
flaw-induced fractureQ17. Phase diagrams are maps that help us track microstructural development during the slow cooling of an alloy. The Fe-Fe3C (iron carbide) phase diagram is an example of a ______________ diagram, with special relevance to steelmaking.
temperature versus time
eutectoid
eutecticQ18. Quenching eutectoid steel below about 200 °C initiates the formation of martensite because the _______________ the austenite phase has become too great.
instability of
specific volume of
diffusion of carbon withinQ19. Electronic conduction in an _____________ semiconductor is the result of the promotion of an electron from the valence band up to the conduction band across an energy band gap.
eccentric
extrinsic
intrinsicQ20. Combining the extrinsic behavior with the intrinsic on the Arrhenius plot produces a stable level of conductivity at ______________ temperatures.
intermediate
relatively low
relatively highMore Quiz Answers >>
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