JNTU
JNTU B.Tech II METALLURGY AND MATERIAL SCIENCE Previous Question Paper (May/June - 2019 - R16)
Note: This question paper contains two parts A and B. 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
Differentiate between metal and alloy.
Answer
A metal is a pure elemental substance characterized by high electrical and thermal conductivity, ductility, and a lustrous appearance, consisting of atoms of a single chemical element. An alloy is a metallic substance composed of two or more elements, where at least one is a metal, combined to enhance specific mechanical or chemical properties such as strength, hardness, or corrosion resistance.
Lattice parameter of a FCC crystal is 3.61A0. Calculate atomic density in (111), (110) and (100) planes.
Answer
For an FCC crystal, the atomic density (planar density) is calculated as the number of atoms centered on the plane divided by the area of the plane. Given the lattice parameter a = 3.61 Å, the atomic density is calculated as follows:
- (100) plane: The plane contains 4 corner atoms (each contributing 1/4) and 1 center atom, totaling 2 atoms. The area is a2. Atomic density = 2 / (3.61)2 = 0.153 atoms/Å2.
- (110) plane: The plane contains 4 corner atoms (each contributing 1/4) and 2 face-centered atoms (each contributing 1/2), totaling 2 atoms. The area is a × (a√2) = a2√2. Atomic density = 2 / ((3.61)2 × 1.414) = 0.108 atoms/Å2.
- (111) plane: The plane contains 3 corner atoms (each contributing 1/6) and 3 face-centered atoms (each contributing 1/2), totaling 2 atoms. The area is (√3/4) × (a√2)2 = (√3/2)a2. Atomic density = 2 / (0.866 × (3.61)2) = 0.177 atoms/Å2.
Define Gibb’s phase Rule.
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List the different methods to construct the phase diagrams.
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Define hardenability and what factors it effects.
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Which alloy of Fe-Fe3C system has the lowest melting point?
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What is carbon equivalent?
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Distinguish between macrostructure and micro structure.
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Distinguish between glasses and cermets.
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Write the applications of polymers.
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Part B
State Hume-Rothery’s rules for the formation of substitutional solid solution.
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Define solid solution and explain about substitutional solid solutions with suitable examples.
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Calculate the packing factor for HCP.
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Explain about density calculations of crystal structures.
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Draw neatly and explain the phase diagram where two components are completely soluble in liquid state and partly insoluble in solid state (with example).
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What is Lever rule? Apply it to phase equilibrium in an alloy of 15% B and 85% A when a liquid of 45% B is in equilibrium with a solid solution of 95% A.
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What is Isomorphous alloy system? Explain with suitable example.
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Construct the TTT diagrams for 0.8wt% carbon steels.
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What is heat treatment and explain its effect?
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Distinguish between annealing and normalizing.
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Write the composition, properties and applications of the following:
Duralumin
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Cartridge brass.
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Differentiate between white Iron and grey cast Iron.
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Explain why extensive coring occurs in bronzes compared to brasses.
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Enumerate the characteristics, properties and applications of crystalline ceramics.
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Write short notes on:
cermets.
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polymers.
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