Chp. 5

Front 1

1. If a transformation from solid to liquid occurs such that the solid and liquid are always in equilibrium, than the transformation is ______

Back 1

reversible.

Front 2

2. A transformation occurs in a material, and the Gibbs free energy change in the material is negative. The transformation is ___________

Back 2

spontaneous.

Front 3

3. When α-phase iron is in equilibrium with iron carbide, the iron atoms in the two phases have equal_________________

Back 3

chemical potential.

Front 4

4. Nickel and silver have lattice parameters of 0.352 nm and 0.408 nm, respectively, an electronegativity of 1.8 for each, an FCC structure, and a similar valence. Should they be able to form a continuous-solid solution?

Back 4

No

Front 5

5. In a phase diagram, the ________ line gives the temperature where the first solid forms upon cooling an alloy of given composition C0 from the liquid phase.

Back 5

liquidus

Front 6

6. In a phase diagram, the _______ line gives the temperature where the first liquid forms upon heating an alloy of given composition C0 from the solid phase.

Back 6

solidus

Front 7

7. The lattice parameter of nickel is 0.352 nm, and for copper it is 0.363 nm. The electronegativities are 1.8 and 1.9, respectively, and they are both FCC metals. It is expected that there is __________ solid solubility of nickel in solid copper at elevated temperature.

Back 7

continuous

Front 8

8. When a liquid copper-nickel alloy is rapidly cooled, the center of the grains has a higher concentration of nickel atoms than the average concentration. This is __________

Back 8

coring.

Front 9

9. The purity of an alloy is given by the chemical ___________

Back 9

composition.

Front 10

10. The weight ________ gives the weight of material present in each phase of a two-phase region, but this says nothing about the phase purity.

Back 10

fraction

Front 11

11. For a binary phase diagram in a two-phase region, use the ______ rule to find the atom or weight fraction of the phases present.

Back 11

lever

Front 12

12. The α _______ line in a phase diagram separates the α-phase field from the α+β-phase field, and it gives the maximum solubility of the B-type atoms in the A-type crystal.

Back 12

solvus

Front 13

13. Solders are made from metals with a(n) _________ phase diagram, because alloys of the metals melt at a temperature lower than that of either of the two components individually.

Back 13

eutectic

Front 14

14. When two elements form a eutectic phase diagram, in the eutectic reaction the atoms of the solid elements ___________ or ___________.

Back 14

segregate or separate.

Front 15

15. At a pressure of 1 atmosphere, a mixture of two metals (A and B) has the three phases α, β, and γ in equilibrium. Can the temperature be changed and still have the α, β, and γ phases in equilibrium?

Back 15

No

Front 16

16. At a pressure of 1 atmosphere, a mixture of two metals (A and B) has the two phases α and β equilibrium at the selected temperature (T). Can the chemical composition of the α phase be changed by adding more A-type atoms at temperature (T)?

Back 16

No

Front 17

17. In a(n) _________ reaction, liquid transforms to two solids α and β.

Back 17

eutectic

Front 18

18. In a(n) _________ reaction, one solid γ phase transforms to two solids α and β.

Back 18

eutectoid

Front 19

19. In a(n) _________ reaction, one solid α phase and a liquid phase react to form one solid phase β.

Back 19

peritectic

Front 20

20. In a(n) _________ reaction, two solid phases α and γ react to form one solid phase β.

Back 20

peritectoid

Front 21

21. The microstructure of the grains of solid α and β phases that form in the lead-tin eutectic reaction is ______ or ______ of the α and β phases.

Back 21

plates or layers

Front 22

22. If elements A and B chemically bond to each other more strongly than a random mixture of A and B elements chemically bond, it is expected that a ________ of A and B should form.

Back 22

compound

Front 23

23. The Ga-As phase diagram has a compound GaAs (γ-phase) that is a single vertical line at 50 atomic % As. Can γ-phase be produced that has 55 atomic % As?

Back 23

No

Front 24

24. An intermediate ______ can have a wider region of possible compositions than does an intermediate compound.

Back 24

phase

Front 25

25. When an intermediate phase melts with no change in chemical composition, this is a(n) __________ melting point.

Back 25

congruent

Front 26

26. In the aluminum-nickel phase diagram in Figure 5.15, what is the reaction type that leads to the formation of Al3Ni at 854°C?

Back 26

Peritectic

Front 27

27. A(n) __________ reaction is when one liquid transforms to another liquid and a solid upon cooling.

Back 27

monotectic

Front 28

28. In polymer blends, the enthalpy of __________ is determined from the experimentally determined interaction parameter.

Back 28

interaction

Front 29

29. If an iron-0.77 % C steel is very slowly cooled from 800°C to room temperature, the expected microstructure is described as _________

Back 29

pearlite.

Front 30

30. If an iron-0.77 % C steel is very rapidly cooled from 800°C to room temperature, the expected microstructure is described as __________

Back 30

martensite.

Front 31

31. If as-quenched martensite is heated to 500°C for one hour, it is then _________ martensite.

Back 31

tempered

Front 32

32. The distortion of the FCC unit cell to a tetragonal unit cell after quenching a carbon steel from 800°C to room temperature is the ____ distortion.

Back 32

Bain

Front 33

33. For a martensitic transformation to be reversible there cannot be the production of ____________ to accommodate strain.

Back 33

dislocations

Front 34

34. In the shape-memory effect in metals, the martensitic transformation must be ________

Back 34

reversible.

Front 35

35. In a reversible martensitic transformation, the Gibbs free energy of the transformation is equal to ______

Back 35

zero.

Front 36

36. For a blend of long-chain molecules, if the enthalpy of mixing is positive, it is expected that the polymers should mix in the liquid at all temperatures above the melting temperature.

Back 36

False

Front 37

1. At the equilibrium melting temperature of a solid, if an atom of solid changes to liquid, the change in the Gibbs free energy is equal to:
(a) The heat of fusion.
(b) Zero.
(c) A negative value.
(d) A positive value.

Back 37

(b) Zero.

Front 38

2. At a temperature below the melting temperature of the solid, if a mole of liquid changes to solid, the change in the Gibbs free energy is equal to:
(a) The negative of the heat of fusion.
(b) Zero.
(c) A negative value.
(d) A positive value.

Back 38

(c) A negative value.

Front 39

3. For a given element, which of the following has the greatest entropy?
(a) A perfect single crystal
(b) A polycrystal
(c) A liquid
(d) A vapor

Back 39

(d) A vapor

Front 40

4. Which of the following is not true about a nucleation and growth transformation from a liquid to a solid?
(a) The transformation rate continuously increases with the amount of super-cooling.
(b) The transformation rate is equal to 0 at the equilibrium temperature.
(c) The transformation rate goes to 0 at temperatures approaching 0 kelvin.
(d) The transformation rate reaches a maximum at a temperature between the equilibrium temperature and 0 kelvin.

Back 40

(a) The transformation rate continuously increases with the amount of super-cooling.

Front 41

5. For a mixture of two different elements A and B, at one atmosphere of pressure three phases are in equilibrium (α, β, and liquid), and it is desired to keep all three phases in equilibrium. Which of the following statements is true?
(a) If the temperature is changed, the composition of the α, β, and liquid phases changes.
(b) The composition of the α phase is changed by adding more A-type atoms.
(c) The composition of the liquid phase is changed by adding more A-type atoms.
(d) Nothing can be changed.

Back 41

(d) Nothing can be changed.

Front 42

6. Two phases α and β are in equilibrium, and they are made of A-type and B-type atoms. Which of the following statements is true?
(a) The Gibbs free energies of the α and β phases are equal.
(b) The chemical potentials of the A-type atoms in the α and β phases are equal.
(c) The Gibbs free energies of the α and β phases are equal to 0.
(d) The chemical potentials of the A-type and B-type atoms in the α-phase are equal.

Back 42

(b) The chemical potentials of the A-type atoms in the α and β phases are equal.

Front 43

7. Which of the following is not necessary for a continuous-solid solution?
(a) Similar atomic numbers.
(b) Atomic radii differ by less than 15%.
(c) The same crystal structure.
(d) A similar electronegativity.

Back 43

(a) Similar atomic numbers.

Front 44

8. Which of the following best describes the microstructure resulting from a eutectic reaction?
(a) Alternating grains of α and β-phases.
(b) Grains of the α-phase with precipitate particles of the β-phase.
(c) A volume with only α-phase grains and another volume with only β-phase grains.
(d) The grains contain alternating plates or rods of the α and β phases.

Back 44

(d) The grains contain alternating plates or rods of the α and β phases.

Front 45

10. Iron with 0.20% carbon is a(n)
(a) Cast iron
(b) Hypereutectoid steel
(c) Hypoeutectoid steel
(d) Eutectoid steel

Back 45

(c) Hypoeutectoid steel

Front 46

11. Bainite is formed by the following procedure with a eutectoid composition carbon steel starting at 800°C (1472°F):
(a) Quench to 500°C (932°F), then hold for 100 seconds, then cool to room temperature.
(b) Quench to 600°C (1112°F), then hold for 100 seconds, then cool to room temperature.
(c) Quench to 700°C (1292°F), then hold for 100 seconds, then cool to room temperature.
(d) Quench to room temperature in 10 seconds.

Back 46

(a) Quench to 500°C (932°F), then hold for 100 seconds, then cool to room temperature.

Front 47

12. The highest-strength carbon steels with some ductility have a microstructure described as:
(a) Martensite.
(b) Pearlite.
(c) Bainite.
(d) Tempered martensite.

Back 47

(d) Tempered martensite

Front 48

1. You are asked to design a metal alloy for use in salt water. The most important design parameter is corrosion resistance followed by other mechanical properties such as yield strength. It is known that dissimilar metals in contact in salt water can result in corrosion of one of the materials. What type of metal alloy phase diagrams should you consider first for this application?
(a) Continuous solid solution
(b) Eutectic
(c) Compound formation
(d) Peritectic

Back 48

(a) Continuous solid solution

Front 49

2. You are asked to design a metal alloy for a high temperature application. What type of metal alloy phase diagrams should you consider first for this application?
(a) Continuous solid solution
(b) Eutectic
(c) Compound formation
(d) Peritectic

Back 49

(c) Compound formation

Front 50

3. You are asked to design a metal alloy for a part with a room temperature application.
The part is to be made by casting the metal into shape. When casting the part, liquid
metal is poured into a mold that has a cavity with the shape of the part. To reduce cost by
conserving energy and to utilize an inexpensive furnace that does not have a high
temperature capability, it is desired that the metal alloy not have a high melting
temperature. What type of metal alloy phase diagrams should you consider first for this
part?
(a) Continuous solid solution
(b) Eutectic
(c) Compound formation
(d) Peritectic

Back 50

(b) Eutectic