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
- covalent
Q2. Glasses are considered a category separate from ceramics because their chemistry is different, even though their atomic structure is the same.
- True
- False
Q3. 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
- semiconductor
Q4. Semiconductors are considered a category separate from metals because their electrical conductivity is different.
- True
- False
Q5. 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
- breakage
Quiz 02: Thing 2
Q1. Aluminum metal is an example of a ______________.
- simple cubic crystal structure
- body-centered cubic crystal structure
- face-centered cubic crystal structure
Q2. The vacancy and the interstitial are two common types of point defects in metallic crystal structures.
- True
- False
Q3. The Arrhenius relationship shows that the rate of chemical reactions increases _______________ temperature.
- linearly with
- exponentially with
- with the fourth power of
Q4. The Arrhenius plot is a linear set of data points in which the logarithm of rate is plotted against the ____________.
- absolute temperature in K
- inverse temperature in K-1
- temperature in °C
Q5. 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=1
Q6. The gas constant, R, is equal to _______________ times the Boltzmann’s constant, k.
- 1024
- Avogadro’s number
- 10-24
Q7. The gas constant, R, is an appropriate term for equations describing gas phases and ________________ processes.
- solid-state
- no other
- all other
Q8. The energy needed to produce a single vacancy, Ev, is the same as the activation energy, Q.
- True
- False
Q9. Solid-state diffusion occurs in the face centered cubic structure of aluminum by individual aluminum atoms hopping into _______________ sites.
- adjacent occupied
- adjacent interstitial
- adjacent vacant
Q10. 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 law
Q12. 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/s
Quiz 01: Thing 3
Q1. An edge dislocation corresponds to an extra ______________.
- full plane of atoms
- cluster of atoms
- half-plane of atoms
Q2. An edge dislocation is a linear defect with the Burgers vector _______________ to the dislocation line.
- at a 45 degree angle
- perpendicular
- parallel
Q3. Crushing an empty soda can made of aluminum alloy is an example of ______________.
- viscous deformation
- plastic deformation
- elastic deformation
Q4. Plastic deformation by dislocation motion is a ___________ alternative to deforming a defect-free crystal structure.
- high-stress
- low-stress
- stress-free
Quiz 02: Thing 4
Q1. The first of the “big four” mechanical properties obtained in the tensile test is ___________________.
- yield strength
- elastic modulus
- tensile strength
Q2. The tensile strength is ___________ the yield strength for typical metal alloys.
- greater than
- about the same as
- less than
Q3. The ductility corresponds to the ______________.
- strength at failure
- total amount of elastic deformation
- strain at failure
Q4. The Elastic Modulus is given by ______________.
- Hooke’s Law
- Poisson’s ratio
- Ohm’s Law
Q5. The yield strength corresponds to ______________.
- an offset of 0.2%
- an offset of 0.1%
- the point of tangency where plastic deformation first begins
Q6. The stress versus strain curve shows that a metal alloy becomes weaker beyond the tensile strength.
- True
- False
Q8. 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 axis
Q9. The Toughness or work-to-fracture is the total area under the stress versus strain curve.
- True
- False
Quiz 01: Thing 5
Q1. “Creep” deformation describes the behavior of materials being used at high temperatures under high pressures over _____________ time periods.
- long
- intermediate
- short
Q2. 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
- False
Q3. In the simplest sense, the creep test is essentially a tensile test done at a high temperature under ____________ load.
- a fixed
- no
- a variable
Q4. A linear portion of the strain versus time plot corresponds to the ______________ stage of the overall creep curve.
- secondary
- tertiary
- primary
Q5. 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
- tertiar
Q6. 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
- False
Q7. 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 hour
Q8. For high temperature creep deformation in ceramic materials, a common mechanism is ______________.
- dislocation climb
- viscous flow (molecules sliding past one another)
- grain boundary sliding
Quiz 02: Thing 6
Q1. The ductile-to-brittle transition was first discovered in conjunction with the failure of ______________
- the Queen Mary
- the Titanic
- Liberty Ships
Q2. The impact energy is an indicator of whether a fracture is ductile or brittle, as measured by the ____________ test
- creep
- tensile
- Charpy
Q3. 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
- brittle
Q4. 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
- faster
Quiz 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 size
Q2. We use the example of __________________ to illustrate concern about a famous “critical flaw.
- Liberty Ships
- the Hindenburg
- the Liberty Bell
Q3. 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 fracture
Q4. The design plot shows stress as a function of time.
- True
- False
Q5. 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
- maximum
Q6. 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 deformatio
Q7. The stress versus strain curve for a sample with a critical pre-existing flaw looks like ______________.
- a regular stress versus strain curve but with a lower value of Y.S.
- a regular stress versus strain curve but with a higher value of Y.S.
- that of a brittle cerami
Q8. 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 quickly
Q9. “Flaw-induced fracture” is also known as “catastrophic fast fracture.”
- True
- False
Quiz 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 as
Q2. 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
- False
Q3. The fatigue curve is a plot of breaking stress versus ______________.
- temperature
- time
- the number of stress cycles
Q4. 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-half
Q5. Fatigue is the result of a critical flaw built up ______________
- prior to being put into service
- instantly
- after a large number of stress cycles
Q6. 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 a relatively low stress until the flaw size reaches the “flaw-induced fracture” segment of the design plot.
- True
- False
Quiz 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
- eutectic
Q2. 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
- False
Q3. In the important Fe – Fe3C (iron carbide) phase diagram, steel making is described by slow cooling through the ______________ reaction
- eutectic
- melting
- eutectoid
Q4. 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 tin
Q5. Heat treatment can be defined as the time-independent process of producing a desired microstructure.
- True
- False
Q6. Previously (in Thing 2), we saw that diffusion increases as temperature increases. Instability ______________ as temperature decreases.
- increases
- decreases
- stays about the same
Q7. 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 temperatur
Q8. The “knee-shaped” curve of the TTT diagram for eutectoid steel is a good example of the competition between instability and ______________.
- stability
- diffusion
- radioactivity
Q9. 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 sizes
Q10. 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 temperatures
Quiz 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 Waals
Q2. 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
- weights
- energy
Q3. 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
- Arrhenius
Q4. In the face centered cubic structure of aluminum, solid-state diffusion occurs by individual aluminum atoms hopping into adjacent interstitial sites
- True
- False
Q5. ___________________ is a linear defect with the Burgers vector perpendicular to the dislocation line.
- An interstitial
- A vacancy
- An edge dislocation
Q6. 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
- plastic
Q7. 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
- False
Q8. 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
- plastic
Q9. 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 sliding
Q10. 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
- low
Q11. 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 tes
Q12. 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
- False
Q13. 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 applications
Q14. The design plot monitors stress as a function of ______________.
- flaw size, a.
- strain
- time
Q15. 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
- False
Q16. 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 a relatively low stress until the flaw size reaches the ______________ segment of the design plot.
- yield stress
- general yielding
- flaw-induced fracture
Q17. 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
- eutectic
Q18. Quenching a 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 within
Q19. 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
- intrinsic
Q20. Combining the extrinsic behavior with the intrinsic on the Arrhenius plot produces a stable level of conductivity at ______________ temperatures.
- intermediate
- relatively low
- relatively high
More Quiz Answers>>
Materials Science: 10 Things Every Engineer Should Know Quiz Answers
What is Palliative Care? Coursera Quiz Answers
A Law Student’s Toolkit Coursera Quiz Answers
