MSE 201 Material Science Assignment Make Up Exam 2017

MSE 201 Material Science Assignment Make Up Exam 2017

Questions are based on Callister & Rethwisch, Materials Science and Engineering: An Introduction, 9th Edition

1-14 question: 5 point each
14-18 questions: 7.5 point each

1. The chemical composition of the repeat unit for nylon 6,6 is given by the formula C12H22N2O2. Atomic weights for the constituent elements are AC = 12, AH = 1, AN = 14, and AO = 16. According to this chemical formula (for nylon 6,6), what is the percent (by weight) of carbon in nylon 6,6 ? What type(s) of bonding would be expected for bronze (a copper-tin alloy)?
2. What are the Miller indices for the plane shown in the following cubic unit cell?
3. A hypothetical metal has the BCC crystal structure, a density of 7.24 g/cm3, and an atomic weight of 48.9 g/mol. What is the atomic radius of this metal?
4. Calculate the number of vacancies per cubic meter at 1000°C for a metal that has an energy for vacancy formation of 1.22 eV/atom, a density of 6.25 g/cm3, and an atomic weight of 37.4 g/mol.
5. What is the composition, in weight percent, of an alloy that consists of 94.1 at% Ag and 5.9 at% Cu? The atomic weights for Ag and Cu are 107.87 g/mol and 63.55 g/mol, respectively.
6. Calculate the diffusion coefficient for copper in aluminum at 600C. Preexponential and activation energy values for this system are 6.5 10–5 m2/s and 136,000 J/mol, respectively.
7. Atoms of which of the following elements will diffuse most rapidly in iron?

(A) Mo
(B) C
(C) Cr
(D) W

9. A cylindrical specimen of brass that has a diameter of 20 mm, a tensile modulus of 110 GPa, and a Poisson’s ratio of 0.35 is pulled in tension with force of 40,000 N. If the deformation is totally elastic, what is the strain experienced by the specimen?
10. The following figure shows the tensile stress-strain curve for a plain-carbon steel.

(a) What is this alloy’s tensile strength?
(b) What is its modulus of elasticity?
(c) What is the yield strength?

11. Plastically deforming a metal specimen near room temperature generally leads to which of the following property changes?

(A) An increased tensile strength and a decreased ductility
(B) A decreased tensile strength and an increased ductility
(C) An increased tensile strength and an increased ductility
(D) A decreased tensile strength and a decreased ductility

12. A dislocation formed by adding an extra half-plane of atoms to a crystal is referred to as a (an)

(A) Screw dislocation
(B) Vacancy dislocation
(C) Interstitial dislocation
(D) Edge dislocation

13. Estimate the theoretical fracture strength (in MPa) of a brittle material if it is known that fracture occurs by the propagation of an elliptically shaped surface crack of length 0.25 mm that has a tip radius of curvature of 0.004 mm when a stress of 1060 MPa is applied.
14. Which type of fracture is associated with intergranular crack propagation?

(A) Ductile
(B) Brittle
(C) Either ductile or brittle
(D) Neither ductile nor brittle

15. Once a system is at a state of equilibrium, a shift from equilibrium may result by alteration of which of the following?

(A) Pressure
(C) Temperature
(B) Composition
(D) All of the above

16. From the lead–tin phase diagram given below which phases/phase combinations is present for an alloy of composition 46 wt% Sn–54 wt% Pb that is at equilibrium at 44^oC?
17. On the basis of accompanying isothermal transformation diagram for a 0.45 wt% C iron-carbon

alloy, what is the heat treatment used to isothermally convert a microstructure that consists of proeutectoid ferrite and fine pearlite into one that is composed of proeutectoid ferrite and martensite?

18. Schematic room-temperature microstructures for four iron–carbon alloys are as follows. Rank these microstructures (by letter) from the hardest to the softest.

Course: MSE 201 Structure and Properties of Engineering Materials
School: North Carolina State University

• Due Date (Double Check):