MSE 2090 Section 2-3
Final Exam: Phase Diagrams, Phase Transformations, Polymers,
Comprehensive,
(BURNS: Corrosion)
180 minutes
350 points
Name: (also write your last name on top of every page)
Pledge:
Useful constants:
k = 8.62x10-5 eV/atom-K = 1.38x10-23 J/atom-K
Na = 6.02x1023 atoms/mole
R = 8.31 J/mole-K
1 eV = 1.6 x 10-19 J
Charge of one electron = 1.6 x 10-19 C
,QUICK FACTS (8 Points Each; 200 Total Points):
Multichoice – Circle EACH correct answer; there can be between 1 and 4 correct answers for
each problem.
Matching – use each choice once.
1. Which of the following is a single phase?
a. A solid solution of Cu and Ni
b. Martensite
c. A mixture of solid Si and liquid Si
d. A lead-tin eutectic structure
2. Pure Fe is found to form in α, β, δ, and γ solids depending on temperature and pressure.
These forms can be referred to as:
a. Phases
b. Isomers
c. Isotopes
d. Allotropes
3. Two elements exhibit an isomorphous binary phase diagram (i.e., complete solid solubility).
Which of the following MUST be TRUE?
a. The elements form intermetallic compounds
b. The elements have the same crystal structure
c. The elements have similar electronegativities
d. There are no two phase regions on the phase diagram.
4. An equilibrium solid phase is a part of a material system volume that has:
a. No grain boundaries
b. A composition that will not change as the temperature and pressure of the system are
varied
c. A uniform composition for a given set of temperature and pressure conditions
d. Uniform physical characteristics (i.e. crystal structure)
5. Match each to its definition:
a. 3 Eutectic
b. 1 Eutectoid
c. 2 Peritectic
d. 4 Peritectoid
,6. During solidification, a large undercooling:
a. Decreases the nucleation barrier (ΔG*)
b. Increases the nucleation rate
c. Increases the critical nucleus size
d. Increases the melting point
7. We cool a liquid phase. When does homogenous nucleation of a solid phase occur?
a. When the temperature reaches the equilibrium melting point
b. When a nucleus of any size is created
c. When a nucleus of size greater than the critical size is created
d. When the driving force for solidification (energy/vol) is > 0
8. Which of the following reactions can occur in an eutectoid steel?
a. Pearlite to martensite
b. Pearlite to bainite
c. Austenite to martensite
d. Austenite to pearlite
9. Which of the following slow (equilibrium) cooling paths produces pro-eutectoid cementite?
a. 1
b. 2
c. 3
d. 4
10. Four pots of steel (identical in composition) are cooled from austenite to room temperature
via different processing cycles (i.e., different heating / cooling steps). Samples from these
four pots are then tensile tested and found to have different strengths. Why might the
strengths differ?
a. Different grain sizes
b. Different crystal structures
c. Different microstructures
d. Different cold working cycles
, 11. Molecular weights of polymers:
a. Are distributed (i.e., not all chains in a polymer are the same weight)
b. Are generally about the same as for metals
c. Do not affect the mechanical properties
d. Do affect the melting temperature
12. Which of the following statements is FALSE about polymers:
a. Linear (unbranched) polymer molecules are perfectly straight.
b. The degree of polymerization depends on the repeat unit molecular weight
c. A cross-linked polymer occurs when adjacent linear chains are joined to one another by
covalent bonds
d. Polymers do not form crystals, even partially
13. Polymers have much lower melting points than most metals because:
a. Metals are better thermal conductors
b. Bonds between polymer macro-molecules are weak secondary bonds
c. The bonds on the macro-molecular backbones are easily broken
d. Due to the fact that covalent bonds are not primary bonds
14. Match each of the following polymer characteristics with the best description:
a. Isomerism 4
b. Structure 2
c. Degree of Polymerization 1
d. Copolymerization 3
1. Number of repeat units in the chain
2. Variations include linear, branched, and cross-linked
3. Variations include block, random, and alternating
4. Variations include atatic, isotactic, and syndiotactic
15. What of the following are true regarding viscoelastic behavior in polymers:
a. It can be described by the relaxation modulus
b. It is independent of loading rate
c. When the stress is removed the deformation is completely recovered
d. Occurs only at temperatures below the glass transition temperature
Final Exam: Phase Diagrams, Phase Transformations, Polymers,
Comprehensive,
(BURNS: Corrosion)
180 minutes
350 points
Name: (also write your last name on top of every page)
Pledge:
Useful constants:
k = 8.62x10-5 eV/atom-K = 1.38x10-23 J/atom-K
Na = 6.02x1023 atoms/mole
R = 8.31 J/mole-K
1 eV = 1.6 x 10-19 J
Charge of one electron = 1.6 x 10-19 C
,QUICK FACTS (8 Points Each; 200 Total Points):
Multichoice – Circle EACH correct answer; there can be between 1 and 4 correct answers for
each problem.
Matching – use each choice once.
1. Which of the following is a single phase?
a. A solid solution of Cu and Ni
b. Martensite
c. A mixture of solid Si and liquid Si
d. A lead-tin eutectic structure
2. Pure Fe is found to form in α, β, δ, and γ solids depending on temperature and pressure.
These forms can be referred to as:
a. Phases
b. Isomers
c. Isotopes
d. Allotropes
3. Two elements exhibit an isomorphous binary phase diagram (i.e., complete solid solubility).
Which of the following MUST be TRUE?
a. The elements form intermetallic compounds
b. The elements have the same crystal structure
c. The elements have similar electronegativities
d. There are no two phase regions on the phase diagram.
4. An equilibrium solid phase is a part of a material system volume that has:
a. No grain boundaries
b. A composition that will not change as the temperature and pressure of the system are
varied
c. A uniform composition for a given set of temperature and pressure conditions
d. Uniform physical characteristics (i.e. crystal structure)
5. Match each to its definition:
a. 3 Eutectic
b. 1 Eutectoid
c. 2 Peritectic
d. 4 Peritectoid
,6. During solidification, a large undercooling:
a. Decreases the nucleation barrier (ΔG*)
b. Increases the nucleation rate
c. Increases the critical nucleus size
d. Increases the melting point
7. We cool a liquid phase. When does homogenous nucleation of a solid phase occur?
a. When the temperature reaches the equilibrium melting point
b. When a nucleus of any size is created
c. When a nucleus of size greater than the critical size is created
d. When the driving force for solidification (energy/vol) is > 0
8. Which of the following reactions can occur in an eutectoid steel?
a. Pearlite to martensite
b. Pearlite to bainite
c. Austenite to martensite
d. Austenite to pearlite
9. Which of the following slow (equilibrium) cooling paths produces pro-eutectoid cementite?
a. 1
b. 2
c. 3
d. 4
10. Four pots of steel (identical in composition) are cooled from austenite to room temperature
via different processing cycles (i.e., different heating / cooling steps). Samples from these
four pots are then tensile tested and found to have different strengths. Why might the
strengths differ?
a. Different grain sizes
b. Different crystal structures
c. Different microstructures
d. Different cold working cycles
, 11. Molecular weights of polymers:
a. Are distributed (i.e., not all chains in a polymer are the same weight)
b. Are generally about the same as for metals
c. Do not affect the mechanical properties
d. Do affect the melting temperature
12. Which of the following statements is FALSE about polymers:
a. Linear (unbranched) polymer molecules are perfectly straight.
b. The degree of polymerization depends on the repeat unit molecular weight
c. A cross-linked polymer occurs when adjacent linear chains are joined to one another by
covalent bonds
d. Polymers do not form crystals, even partially
13. Polymers have much lower melting points than most metals because:
a. Metals are better thermal conductors
b. Bonds between polymer macro-molecules are weak secondary bonds
c. The bonds on the macro-molecular backbones are easily broken
d. Due to the fact that covalent bonds are not primary bonds
14. Match each of the following polymer characteristics with the best description:
a. Isomerism 4
b. Structure 2
c. Degree of Polymerization 1
d. Copolymerization 3
1. Number of repeat units in the chain
2. Variations include linear, branched, and cross-linked
3. Variations include block, random, and alternating
4. Variations include atatic, isotactic, and syndiotactic
15. What of the following are true regarding viscoelastic behavior in polymers:
a. It can be described by the relaxation modulus
b. It is independent of loading rate
c. When the stress is removed the deformation is completely recovered
d. Occurs only at temperatures below the glass transition temperature
