£G-180 Supplementary Exam 2018 PDF

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PRIFYSGOL ABERTAWE SWANSEA UNIVERSITY College of Engineering SEMESTER 1 EXAMINATIONS Supplementary 2018

EG-180

Introduction to Materials Engineering YEAR 1 Only University Calculators are permitted Translation dictionaries are not permitted, but an English dictionary may be borrowed from the invigilator on request

Time allowed:

2 hours Answer All questions This is a closed book examination

This is a multiple choice examination and any answer not marked clearly on the answer sheet provided will not be considered. Please insert any standard constants here:R = 8.314JK-1

PLEASE NOTE THAT THIS EXAMINATION PAPER IS PRINTED ON BOTH SIDES

TURN OVER Page 1 of 15

[1 Mark]

Question 1: Which of the following is classed as a materials property? (a) (b) (c) (d) (e)

Quantity Availability Mechanical Cost None of the above

[2 Marks]

Question 2:

Which of the following equations is suitable for calculating a materials stiffness (E)? Strain /Stress (b) E = Stress / Strain (c) E = Force / Area (d) E = Plastic deformation/ Elasticdeformation

(a) E =

(e) All of the above

[4

Question 3:

Marks] If a copper wire of original length 400mm is pulled in tension with a stress of 264MPa determine the resultant extension to 2 significant figures,

assuming

pure elastic

deformation and E = 110GPa for Cu.

Original length, lo 400mm

(a) 0.96mm (b) 9.6mm (c) 1.6mm (d) 16mm (e) 2.510mm

Extension, Δl Stress 264MPa Page 2 of 15

TURN OVER Graph 1 - Stress/Strain plot

[4 Marks]

Question 4: From the plot in Graph 1 determine the Young’s Modulus? (a) (b) (c) (d) (e)

7GPa 57GPa 105GPa 285MPa None of the above

[1 Mark]

Question 5: From the plot in Graph 1 determine the 0.2% proof stress: (a) (b) (c) (d) (e)

210MPa 600MPa 200MPa 300MPa None of the above Page 3 of 15

TURN OVER [4 Marks]

Question 6:

From the plot in Graph 1 determine the maximum load that can be sustained by a cylindrical specimen having an original diameter of 12.8mm: (a) 77.2kN (b) 308.8kN (c) 7.68kN (d) 57905N (e) None of the above

[2 Marks]

Question 7:

From the plot in Graph 1 determine the change in length of a specimen originally 250mm in length that is subjected to a tensile stress of 480MPa at point A: (a) 0.1mm (b) 0.25mm (c) 15mm (d) 25mm (e) None of the above

Page 4 of 15

TURN OVER Table 1 - Periodic table of elements

[3 Marks]

Question 8:

Given the periodic table shown above (Table 1) determine the electron configuration for Iron: (a) 1s22s22p63s23p63d64s2 (b) 1s22s22p63s23p64s13d6 (c) 1s22s22p63s23p64s33d5 (d) 1s22s22p63s23p63d64s1

(e) None of the above [2 Marks]

Question 9:

Given the periodic table shown above (Table 1) determine the valence electron configuration for Sodium: 2

(a) 3s 1 (b) 3s 6 (c) 4s 1 (d) 4s (e) None of the above Page 5 of 15

TURN OVER [2 Marks]

Question 10:

Which of the following are not considered a primary bonding mechanism? (a) Ionic (b) Covalent (c) Van der Waals (d) Metallic (e) None of the above [2 Marks]

Question 11: Which of the following unit cells has a coordination number of 8? (a) (b) (c) (d) (e)

HCP BCC FCC Simple Cubic None of the above

[3 Marks]

Question 12:

Determine the atomic packing factor [APF] for the simple cubic unit cell: (a) (b) (c) (d) (e)

0.52 0.68 0.74 1 None of the above

[2 Marks]

Question 13:

Complete the following sentence; In the FCC close packed system slip occurs preferentially……. (a) (b) (c) (d) (e)

Always along the cube edges On the least dense planes in the most dense direction On the most densely packed planes in the least dense direction On the most densely packed planes in the most densely packed direction None of the above

Page 6 of 15

TURN OVER Unit Cell - 1

[2 Marks]

Question 14:

From Unit Cell 1 shown above describe the Direction from O to A using correct Miller notation: (a) (011) (b) [100] (c) [011] (d) (111) (e) None of the above

[3 Marks]

Question 15:

From Unit Cell 1 shown above describe the Direction from O to B using correct Miller notation: (a) (101) (b) (010) (c) [101] (d) [010] (e) None of the above Page 7 of 15

TURN OVER [2 Marks]

Question 16:

From Unit Cell 1 shown on page 7, describe the Direction from C to O using correct Miller notation: (a) (b) (c) (d) (e) None of the above Question 17:

[3 Marks]

From Unit Cell 2 describe Plane A using correct Miller notation:

Unit Cell – 2

(a) (b) (c) (d) (e) None of the above

Question 18:

[3 Marks]

From Unit Cell 2 describe Plane B using correct Miller notation: (a) (b) (c) (d) (e)

(320) (230) (110) [230] None of the above

Page 8 of 15

TURN OVER [2 Marks]

Question 19:

In solid state diffusion describe the relationship between the Diffusion coefficient and Temperature: (a) (b) (c) (d) (e)

Linear Inverse Exponential Proportional None of the above

Table 2 – Results from diffusion experiments with pure Silver Temperature (°C)

D - Single crystal (m2s-1)

D - Polycrystal (m2s-1)

700

5.00 x 10-15

6.31 x 10-15

1000

1.26 x 10-12

1.26 x 10-12

[5 Marks]

Question 20:

Using table 2 calculate the activation energy for self diffusion in a single crystal: (a) 189.8kJmol-1 (b) 103.4kJmol-1 (c) 1.571kJmol-1 (d) 230.27kJmol-1 (e) 103.39kJmol-1 [5 Marks]

Question 21:

Using table 2 calculate the activation energy for self diffusion in a polycrystal: (a) 189.8kJmol-1 (b) 138.05kJmol-1 (c) 107.85kJmol-1 (d) 89.67kJmol-1 (e) 181.8kJmol-1

Page 9 of 15

TURN OVER [2 Marks]

Question 22:

Which of the following statements best describe the reason for the difference in the activation energy for diffusion between the single crystal and the polycrystal? (a) There is no difference since they have the same chemistry (b) Activation energy for diffusion in polycrystals is higher due to the presence of grain boundaries (c) Some difference due to a change in chemistry (d) Activation energy for diffusion in polycrystals is lower due to the presence of grain boundaries (e) None of the above

[1 Mark]

Question 23: Which of the following statements is true (a) (b) (c) (d)

The concentration of vacancies increases with increasing temperature The concentration of vacancies decreases with increasing temperature Vacancy concentration remains constant despite temperature changes The energy required to create a vacancy is higher compared to that of an

interstitial defect (e) None of the above

Page 10 of 15

TURN OVER Graph 2 – Cu – Ni phase diagram

[3 Marks]

Question 24:

Using the Cu – Ni phase diagram plotted in Graph 2 above determine the percentage weight of copper in the liquid phase at 1300°C: (a) (b) (c) (d) (e)

56wt% liquid 54wt% liquid 62wt% liquid 38wt% liquid None of the above

[4 Marks]

Question 25:

Using the lever rule calculate the weight fraction of the solid and liquid phase at 1300°C in the Cu – Ni phase diagram plotted in Graph 2 above: (a) 44% solid to 62% liquid (b) 62% solid to 44% liquid (c) 55.6% solid to 44.4% liquid (d) 44.4% solid to 55.6% liquid (e) None of the above

Page 11 of 15

TURN OVER Graph 3 - Iron – Carbon Phase Diagram

[4 Marks]

Question 26:

Using the Iron – Carbon phase diagram plotted in Graph 3 above, determine the weight fraction of Ferrite (α) for a composition of 0.4%C Steel cooling from point c, at temperature just above the eutectoid temperature 7230C point d. (a) (b) (c) (d) (e)

0.4 0.49 0.51 0.03 None of the above

Page 12 of 15

TURN OVER [3 Marks]

Question 27:

If ceramic structures are determined by the ratio of cation to anion radius then calculate the minimum cation to anion radius ratio for a centre of cubic geometry. (a) 0.732 – 1.0 (b) 0.414 – 0.732 (c) 0.225 – 0.414 (d) 0.155 – 0.225 (e)...