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.
Q2. Glasses are considered a category separate from ceramics because their chemistry is different, even though their atomic structure is the same.
Q3. Fiberglass is a good example of a ___________ combining the strength and stiffness of reinforcing glass fibers with the ductility of the polymeric matrix.
Q4. Semiconductors are considered a category separate from metals because their electrical conductivity is different.
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 _____________.
Q1. Aluminum metal is an example of a ______________.
Q2. The vacancy and the interstitial are two common types of point defects in metallic crystal structures.
Q3. The Arrhenius relationship shows that the rate of chemical reactions increases _______________ temperature.
Q4. The Arrhenius plot is a linear set of data points in which the logarithm of rate is plotted against the ____________.
Q5. The activation energy, Q, for a chemical reaction is indicated by the _______________ of the Arrhenius plot.
Q6. The gas constant, R, is equal to _______________ times the Boltzmann’s constant, k.
Q7. The gas constant, R, is an appropriate term for equations describing gas phases and ________________ processes.
Q8. The energy needed to produce a single vacancy, Ev, is the same as the activation energy, Q.
Q9. Solid-state diffusion occurs in the face centered cubic structure of aluminum by individual aluminum atoms hopping into _______________ sites.
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.
Q11. The diffusion coefficient is defined by _______________.
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 _____________.
Q1. An edge dislocation corresponds to an extra ______________.
Q2. An edge dislocation is a linear defect with the Burgers vector _______________ to the dislocation line.
Q3. Crushing an empty soda can made of aluminum alloy is an example of ______________.
Q4. Plastic deformation by dislocation motion is a ___________ alternative to deforming a defect-free crystal structure.
Q1. The first of the “big four” mechanical properties obtained in the tensile test is ___________________.
Q2. The tensile strength is ___________ the yield strength for typical metal alloys.
Q3. The ductility corresponds to the ______________.
Q4. The Elastic Modulus is given by ______________.
Q5. The yield strength corresponds to ______________.
Q6. The stress versus strain curve shows that a metal alloy becomes weaker beyond the tensile strength.
Q8. The elastic “snap back” that occurs at failure is parallel to ______________.
Q9. The Toughness or work-to-fracture is the total area under the stress versus strain curve.
Q1. “Creep” deformation describes the behavior of materials being used at high temperatures under high pressures over _____________ time periods.
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.
Q3. In the simplest sense, the creep test is essentially a tensile test done at a high temperature under ____________ load.
Q4. A linear portion of the strain versus time plot corresponds to the ______________ stage of the overall creep curve.
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.
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.
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.)
Q8. For high temperature creep deformation in ceramic materials, a common mechanism is ______________.
Q1. The ductile-to-brittle transition was first discovered in conjunction with the failure of ______________
Q2. The impact energy is an indicator of whether a fracture is ductile or brittle, as measured by the ____________ test
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 __________.
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.
Q1. We focus on “critical flaws” that ______________.
Q2. We use the example of __________________ to illustrate concern about a famous “critical flaw.
Q3. The design plot is composed of two intersecting segments: yield strength corresponding to general yielding and fracture toughness corresponding to ______________
Q4. The design plot shows stress as a function of time.
Q5. The ______________ flaw size is defined within the design plot at the intersection between the general yielding segment and the flaw-induced fracture segment
Q6. The I in the subscript of the fracture toughness, KIc , refers to ______________ .
Q7. The stress versus strain curve for a sample with a critical pre-existing flaw looks like ______________.
Q8. The benefit of failure by general yielding is that ______________.
Q9. “Flaw-induced fracture” is also known as “catastrophic fast fracture.”
Q1. The fatigue strength that is associated with catastrophic failure after a large number of stress cycles is ______________ the yield strength.
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.
Q3. The fatigue curve is a plot of breaking stress versus ______________.
Q4. The “fatigue strength” is defined as the point where the fatigue curve reaches a value of roughly _____________ of the tensile strength.
Q5. Fatigue is the result of a critical flaw built up ______________
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.
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.
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
Q3. In the important Fe – Fe3C (iron carbide) phase diagram, steel making is described by slow cooling through the ______________ reaction
Q4. The “pasty” quality of lead solders in the lead-tin system can be attributed to ______________.
Q5. Heat treatment can be defined as the time-independent process of producing a desired microstructure.
Q6. Previously (in Thing 2), we saw that diffusion increases as temperature increases. Instability ______________ as temperature decreases.
Q7. Because of the competition between instability and diffusion, the most rapid transformation will occur _______________.
Q8. The “knee-shaped” curve of the TTT diagram for eutectoid steel is a good example of the competition between instability and ______________.
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 ______________.
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 ______________.
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.
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 ___________.
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.
Q4. In the face centered cubic structure of aluminum, solid-state diffusion occurs by individual aluminum atoms hopping into adjacent interstitial sites
Q5. ___________________ is a linear defect with the Burgers vector perpendicular to the dislocation line.
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.
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.
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.
Q9. For high temperature creep deformation in metal alloys, a common mechanism that we illustrated is ______________.
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.
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 ______________.
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.
Q13. The design plot is composed of two intersecting segments: yield strength corresponding to ___________ and fracture toughness corresponding to flaw-induced fracture.
Q14. The design plot monitors stress as a function of ______________.
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.
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.
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.
Q18. Quenching a eutectoid steel below about 200 °C initiates the formation of martensite because the _______________ the austenite phase has become too great.
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.
Q20. Combining the extrinsic behavior with the intrinsic on the Arrhenius plot produces a stable level of conductivity at ______________ temperatures.
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