JNTU
JNTU B.Tech II PHYSICAL METALLURGY Previous Question Paper (April/May - 2018 - R13)
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. Each question carries 10 marks.
Part A
What is crystal structure? Give the coordination numbers of FCC and HCP structures.
Answer
A crystal structure is the orderly, repeating three-dimensional arrangement of atoms in a crystalline solid, defined by its unit cell geometry and atomic positions. The coordination number for both FCC and HCP structures is 12.
Define nucleation and growth during solidification of metals/alloys.
Answer
Nucleation is the initial stage of solidification where small, stable clusters of atoms (nuclei) form within the liquid phase. Growth is the subsequent process where these nuclei increase in size as atoms from the liquid attach to the solid-liquid interface, eventually forming grains.
What is ASTM grain size number? Explain.
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Differentiate between substitutional and interstitial solid solutions.
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Define the terms (i) Intermediate Phases (ii) Intermetallic Compounds.
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What are Hume-Rothery rules?
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Calculate the amount of ferrite and cementite at 0.8% C and 700°C in Fe-C diagram.
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Define the terms (i) Pearlite (ii) Cementite (iii) Austenite.
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Differentiate between bainite and martensite.
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What is the difference between TTT diagram and Phase Diagram?
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Part B
What is Miller Indices? Discuss briefly and give one example.
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With a neat sketch of BCC structure, find effective number of atoms, packing factor and coordination number?
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Prove that the packing factor for HCP cell is 0.74%.
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Explain the terms (i) space lattice (ii) unit cell (iii) lattice parameter.
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What are the important characteristics of grain boundaries? Discuss the role of grain boundaries for low temperature and high temperature applications.
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What is allotropy? Explain different allotropic forms of Iron.
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Explain the nucleation and growth mechanism for the solidification of metals.
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What are the different types of solid solutions? Explain interstitial solid solution with suitable examples.
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Discuss the experimental methods for constructing equilibrium diagrams. Enumerate the advantages and disadvantages of these methods.
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Write the Equation of Gibb’s phase rule? Define and explain each of the terms in the equation.
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What is cooling curve? Draw the cooling curves for binary solid solution alloy and binary eutectic alloy.
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What is precipitation hardening? Describe with one example.
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Calculate the relative amounts of various phases that are present in 0.5% C steel, just above and just below the peritectic temperature.
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Explain the phase changes that take place when eutectoid steel is cooled from 900°C to room temperature?
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Draw iron –iron carbide diagram? Lable all temperatures, phases, reactions and required notations.
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Explain the Following Reaction: (i) Eutectic (ii) Eutectoid.
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Explain the terms (i) Upper Bainite (ii) Lower Bainite (iii) Coarse Pearlite (iv) Fine pearlite (v) Lath martensite.
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‘When martensite form, expansion occurs’. Explain why?
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Differentiate between CCC and TTT diagrams.
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Explain the effect of alloying elements on the formation of Bainite and martensite.
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