JNTU
JNTU B.Tech II METALLURGY AND MATERIALS SCIENCE Previous Question Paper (November/December - 2017 - R15)
Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
Part A
Find the packing efficiency in HCP lattice.
Answer
The packing efficiency of an HCP lattice is 74%. It is calculated by determining the ratio of the volume of atoms in a unit cell to the total volume of the unit cell, where the unit cell contains 6 effective atoms and has a base area of 6√3r2 and height 4r√2/√3.
Lattice parameter of a FCC crystal is 3.61Å calculate atomic density in (111), (110) and (100) planes.
Answer
For an FCC crystal with lattice parameter a = 3.61 Å, the atomic density is calculated as (Number of atoms in the plane) / (Area of the plane):
- (111) plane: Area = (√3/2)a2, Atoms = 2. Density = 2 / (0.866 * 3.612) = 0.177 atoms/Å2.
- (110) plane: Area = a2√2, Atoms = 2. Density = 2 / (1.414 * 3.612) = 0.108 atoms/Å2.
- (100) plane: Area = a2, Atoms = 2. Density = 2 / 3.612 = 0.153 atoms/Å2.
What is the necessity of Alloying?
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Distinguish between Intermetallic Compound and Electron compound.
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What is congruent melting phase?
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Define allotropy and give examples.
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What is ASTM-grain size number? What is its importance?
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Distinguish between ordered and disordered solid solution.
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What is coring and how it can be minimized?
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What are the general requirements of a reinforcing phase?
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Part B
What is an interstitial solid solution, name the five elements which commonly form interstitial solid solutions? What is a grain size? What is a fine grained and coarse-grained material?
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What is crystal system and explain the Brevais lattices? Write explanatory notes ASTM grain size measuring methods.
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Write a note on Transformations of solid state.
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Draw and explain the phase diagram where two components are completely soluble in both liquid and solid state with suitable examples.
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What is the effect of alloying elements on Fe-Fe3C diagram? Draw the TTT diagrams and explain the different cooling rates.
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What is hardenability and how it is measured? Differentiate between Hardening and Tempering.
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What is cast Iron and explain the classification of cast irons? Differentiate between Cu alloys and Al alloys with respect to properties, heat treatment, composition and microstructure.
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Draw and Explain the Cu-Zn phase diagram. Write short notes on Ti alloys.
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Enumerate the characteristics, properties and applications of Polymers.
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Write Short notes on: a) Metal ceramic mixtures. b) C- Composites.
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