Andhra University 2007 B.E material science and engineering - exam paper
Wednesday, 01 May 2013 04:05Web
II Year B.E./B.Tech Degree exam
MATERIAL SCIENCE & ENGINEERING
(Chemical Engineering)
Time: three hours Max.Marks: 75
ques. one is compulsory
ans any 4 from ques. two to 8
All ques. carry equal marks
1. ans the following: (5 x three = 15)
a) discuss DHCrystal and Lattice DH . What do they signify in
bonding?
b) What is configurational entropy? How would you
estimate it?
c) elaborate slip systems? provide slip planes and slip systems
of HCP and FCC structures.
d) discuss the mechanism of fatigue failure of materials.
e) Show the heat treatment cycles for Quenching and
Annealing.
2. a) find and expression for the Bond Energy of A X
kind of crystal in which the anion and catino both are
monovalent.
b) 1st 3 lines from powder trend of a Cubic Crystal
have the subsequent S values, 2.495c, 4.09cm, 4.805cm.
On stretching the cassette film the distance ranging from
the entrance and exit slits of the film is 180mm.
Molybdenum of Ka radiation is used to find the
trend and the Wave length of the radiation is 0.710 A.
Determine the structure and the lattice parameter of
the material.
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3. a) Derive Bragg’s legal regulations of X-ray diffraction. Show that
for any order of reflection n = 1. Briefly analyze the
data found in X-ray diffraction technique using the
metal specimen in the form of powder.
b) Titanium has HCP structure beneath 8800C with a =
2.9650A and c/a ratio of 1.584. If the atomic weight of
titanium is 47.9 g/g atom compute the density of
Titanium. If Titanium reverts to BCC at a temp above
8800C (a = 3.32 A0), compute the change in the Density
during such transformation from HCP to BCC.
4. a) elaborate line defects? With the help of a neat sketch
draw edge dislocation. Show the Burgers circuit and
Burgers vector in the diagram. List the characteristics
of an edge dislocation. discuss the motion of an Edge
dislocation under the influence of Shear stress.
b) An FCC crystal of Aluminium is stressed in [101]
direction, under a stress of 4.24 MN/m2 in tension. On
which of the subsequent systems does slip occur and what
is Critical Resolved shear Stress? The planes and
directions are :
(111) [101] ; (101) [111] ; and (111) [110]
5. a) discuss the Anelastic property (Elastic - After-effect)
of materials with suitable examples. provide the reasons
for Analastic behaviour of materials atomic point of view.
Sketch the Strain Vs time diagram both for loading the
unloading conditions and discuss what is relaxation time?
b) An empirical formula which represents the Strain-
Hardening of behaviour of many engineering materials is:
s1=A(B+et)n
Show that for uniform elongation of such a material
( ) t e = n-B
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6. a) find Griffith’s criterion for brittle failure. Summarise
with suitable example the characteristics of brittle failure.
Compare this with ductile failure.
b) Enumerate the factors improving the Fatigue resistance
for materials. Using S-N diagram compare the Fatigue
behaviour of Ferrous and non-Ferrous materials.
7. a) Draw Iron-Iron Carbide diagram, tag all the Phase
fields. Indicate (i) Eutectic point (ii) Eutectoid point in
the phase diagram. Write the improper phase
transformation reactions at these points.
b) The phase diagram of a Binary system of A and B has
a 3 phase equilibrium at 2500C with composition
of a , Liquid and b phases equal to 10%, 55% and
95% respectively. Just beneath 2500C obtain the
compositions which proetectic phase is 1.5 times the
Eutectic Mixtures.
8. Write detailed notes on any 3 from the subsequent.3x5=15
a) Electron microscopy for observing the micro-structure
b) Role of dislocation in improving mechanical properties
c) Creep in metals - Creep curve
d) Requirements of use of a material in shipping industry
e) Non-destructive testing of materials used in ship building
industry
f) Heat treatment and its objectives
Earning: Approval pending. |