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VTU Mechanical Engineering (Semester 3)
Material Science & Metallurgy
December 2011
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1 (a) Sketch the unit cell of a HCP crystal structure.Calcultate the number of atoms per unit cell.Derive an expression for the density of atomic packing.(Given C=1.633a)
6 M
1 (b) Copper has an atomic radius of 1.28× 10-8cm, a FCC crystal structure ana an atomic weight of 63.5.calculate its density(Avogardo number=6.023×1023
5 M
1 (c) Expalin the different types of surface imperfection,with neat sketches
6 M
1 (d) State and explain the fick's second law of diffusion.
3 M

2 (a) Draw the stress-strain digram of mild steel and describe how the follwing properties can be obtained from the diagram:
Elastic modulus
Ductility
Toughness
7 M
2 (b) A cylindrical speciman of steel having an original diameter of 12.8mm is tensile tested to feature feature and found to have an engineering fracture strenghth ?f of 460 Mpa .if its cross -sectional diameter at the fracture is 10.7mm,determine
The duclicity in term of percent area reduction
The true stress at fracture
6 M
2 (c) Differentiate between the slip and twinning ,with neat sketches
6 M

3 (a) Expalin with a sketches,the ductile to brittle transition in the materials
4 M
3 (b) If the specify surface energy for AL2O3 is 0.9 J/m2,calculate the critical stress required for propagation of an internal crack of length 0.4 mm(E=393 Gpa for AL2O3
5 M
3 (c) draw and explain the S-N curve for steel and aluminium alloy
5 M
3 (d) Define stress relaxation.Derive the corresponing expression
6 M

4 (a) Expalin the homogeneous nucleation.discuss the significance of critical radius of the nucli.
8 M
4 (b) Describe the diffreent types of solids solution
6 M
4 (c) State the gibbs phase rule and explain with a simple example
6 M

5 (a) Consruct a phase digrame for two metals completely soluble in the liqiud state but pertially soluble in solid state
4 M
5 (b) draw the iron-carbon equlibrium diagram and label all the parts
8 M
5 (c) with the help of the diagram in 5(b) expalin the cooling of steel with 0.6% carbon,showing the microstructure at different statges
8 M

6 (a) Draw the TTT digram for plain carbon cutectoid steel and explain the critical cooling rate
7 M
6 (b) Explain any one type of surface hardening,with sketches
6 M
6 (c) Differentiate between the normalization and anneling with sketches
7 M

7 (a) Expalin the different types of cost iron with microstructure
8 M
7 (b) Write a short note on the copper alloys
8 M
7 (c) Explain the modification of AI -Si alloy.
4 M

8 (a) What is a composite material ?how is it classified ?
8 M
8 (b) With a neat skecth, explain any one method for production of fiber reinforced plastic
6 M
8 (c) Briefly discuss the advantages & application of meta matrix composite (MMc)
6 M

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