Short Answer Type Questions
On Solid Solutions
1. Define the following terms: system, state, phase, component, constituent, degrees of freedom, equilibrium.
2. What is an alloy?
3. How many components are found in an alloy?
4. What is meant by base metal?
5. What are alloying elements?
6. How do you distinguish between alloying elements and impuri- ties?
7. Differentiate between substitutional and interstitial solid solutions.
8. State Hume Rothery's rules for formation of substitutional solid solutions.
9. Why is complete intersolubility possible in a substitutional solid. solution but not in an interstitial solid solution?
10. What are intermediate phases?
11. What are intermetallic compounds?
12. What are electron compounds?
On Phase Diagrams
13. Define 'phase'. What different kinds of phases are possible?
14. What is an equilibrium phase diagram?
15. What are the advantages of the equilibrium diagrams.
16. State Gibb's phase rule?
17. What are cooling curves?
18. How do cooling curves aid in determining phase diagrams?
19. What is a liquidus line? A solidus line? A solvus line?
20. What pieces of information can be obtained for each point in a phase diagram?
21. What is a tie-line and what information can it provide?
22. What is a lever-law calculation and what information can it nis provide?
23. What is a three-phase reaction?
24. What do you mean by invariant reactions?
25. Differentiate between eutectic and eutectoid reactions.
26. Distinguish between peritectic and peritectoid reactions.
On Iron-carbon system
27. What do you understand by 'allotropy of iron?'
28. Define ferrite, cementite, austenite, pearlite, martensite, bainite.
29. Why is the iron-carbon equilibrium diagram usually not shown beyond 6.67% carbon?
30. What is steel?
31. What is meant by eutectoid, hypoeutectoid, hypereutectoid steels?
32. How do cast irons differ from steels in terms of carbon content?
Essay Answer Type Questions
On Solid Solutions
1. Discuss the similarities and differences between substitutional and interstitial solid solutions.
On Phase Diagrams
2. What are cooling curves? How does the time-temperature cooling curve of an alloy of eutectic composition differ from that of a pure metal? That of a non-eutectic composition alloy?
3. Explain the rules by which chemical composition and amount of phases can be estimated from phase diagrams.
4. How will you plot binary phase diagram for two metals which are completely soluble in liquid and solid states?
5. How can you construct a phase diagram for binary eutectic alloy system? Explain.
6. Explain the following invariant reactions with reference to a phase diagram:
(a) Eutectic reaction,
(b) Eutectoid reaction, man
(c) Peritectic reaction, and
(d) Peritectoid reaction.
On Iron-Carbon System:
7. What are the micro-constituents of iron-carbon alloys? Explain the general characteristic of each.
8. Draw iron-iron carbide equilibrium diagram and mark on it all salient temperatures and composition fields.
9. Describe the phase changes that occur when a molten 0.35% C steel solidifies and cools slowly from 1700°C to room temperature. Also draw the probable microstructure of steel at about 800°C and 25°C
10. Name phase reactions occurring in Fe-Fe3C system. What are the temperatures and compositions at which they occur?
11. Explain the primary crystallisation of eutectoid steels, hypoeutectoid steels, and hypereutectoid steels.
12. Explain the primary crystallisation of eutectic cast irons, hypoeutectic cast irons, and hypereutectic cast irons.
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