(SEM-III) THEORY EXAMINATION, 2018-19 MATERIAL SCIENCE

Exam Details

Course: B. Tech (Semester III) 1
Subject: Material Science (RME301) 2222
Time Allowed: 3 Hours 3
Total Marks: 70 4

SECTION A: Short Answer Questions

(Attempt all questions. Each question carries 2 marks. Total: 14 marks) 5555
a) Define recrystallization temperature. 6

b) Define 'critical cooling rate' in a TTT diagram with a neat sketch. 7

c) What are refractory materials? Give some examples. 8

d) Define the term strain hardening. 9

e) Differentiate between toughness and resilience. Also, define the endurance limit. 10

f) Why is hardening followed by tempering? 11

g) What are Bravais space lattices? 12

SECTION B: Long Answer Questions

(Attempt any three parts. Each question carries 7 marks. Total: 21 marks) 13131313

a) Define the term diffusion. Explain Fick's law in the case of steady-state diffusion. 14

b) What is Non-Destructive Testing (NDT)? Explain in detail any two NDT methods. 15

c) What is a phase diagram? Draw a neat sketch of the Iron-Carbon diagram and explain the various phases present in it and the important reactions occurring. 16

d) What do you mean by the heat treatment process? Name various types of processes and explain in detail the Nitriding process with its merits and demerits. 17171717

e) What are Ceramics? What are the different types of ceramics? Also, write their properties. 18

SECTION C: Comprehensive/Analytical Questions

(Attempt any one part from each question. Each question carries 7 marks. Total: 35 marks) 19191919

Question 3:

a) Calculation: How many atoms per square millimeter are there on the (100) plane of lead? Lead has an FCC structure. Assume the interatomic distance to be 3.499 Å. 20

b) Calculation: NaCl has an FCC structure. The density of NaCl is 2.18 g/cm³ (Note: Unit inferred as typical for density, text says $2.18~cm^{3}$ likely typo). Calculate the distance between two adjacent atoms. 21

Question 4:

a) What is a dislocation? What are the different types of dislocations? Explain. Draw their neat sketches and mark the Burgers vector in each case. 22

b) Explain the term creep, its mechanism, and its stages. 23

Question 5:

a) Write short notes on Solid solution and its types. 24

b) What do you understand by the lever rule? Determine the mass fraction of the phases present at 184°C in a sample of lead & tin with 45% tin in it. 25

Question 6:

a) Draw and explain the TTT diagram for eutectoid steel. Explain important transformations taking place in it on cooling. 26

b) What are brasses and bronzes? How are they classified? Give the composition, properties, microstructure, and applications of any two of each. 27

Question 7:

a) What are the various methods of plastic processing? 28

b) Explain in detail the classification and applications of composite materials.