Physical Metallurgy Mid - I, September - 2014

1.The role of grains and grain boundaries in the metals and alloys is
  • Improving the magnetic property
  • Improving the melting temperature
  • Changes the phase transformation temperatures
  • Strengthening the metals and alloys
Answer: D
2.Fine grain alloys exhibit
  • High yield strength
  • High fatigue strength
  • High corrosion resistance
  • High melting temperature
Answer: A
3.Find the wrong statement: The most stable arrangement of atoms in a crystal will
  • Minimize the energy per unit volume
  • Preserves the electrical neutrality
  • Satisfies the directionality
  • Maximises the strong ion-ion repulsion
Answer: D
4.Identify the non-electron compounds
  • Mg2Pb
  • AuMg
  • Cu9Al4
  • Ag3Sn
Answer: A
5.The following property does not include in the properties of electron compounds
  • Wide range of composition
  • High ductility
  • High melting points
  • Low hardness
Answer: C
6.Relation between atomic radius ‘r’ and lattice parameter ‘a’ for fcc system is
  • a = 2√2 r
  • a = ¾ r
  • a = √2 r
  • a = 2r
Answer: A
7.The crystal structure of a ductile metal is
  • BCC
  • FCC
  • hcp
  • Simple Cubic
Answer: B
8.Cu-Ni phase diagram is an example for
  • Eutectoid reaction
  • Eutectic system
  • Isomorphous system
  • Peritectic reaction
Answer: C
9.In eutectoid reaction _____________ .
  • Both solute and solvent are miscible in liquid state as well as in solid state
  • Both reactants and products are in solid state
  • Reactants are in liquid state and products are in solid state
  • Solid reacting with liquid forms another solid while cooling
Answer: B
10.Unlimited solubility is observed in ______________ solid solutions.
  • Substitutional
  • Random solid solutions
  • Interstitial solid solutions
  • Regular solutions
Answer: A
11.The c/a ratio of ideal crystal structure is __________________________.
Answer: 1.633
12.Hume-Rothery rules deals with ______________________
Answer: Formation of substitutional solid solutions
13.The number of nearest equidistant neighbouring atoms surrounding any atom under consideration is called as _________________
Answer: Co‐ordination number
14.The upper line in the phase diagram, obtained by connecting the points showing beginning of solidification is called _____________________
Answer: Liquidus line
15.When the atoms of solute substitute for atoms of the solvent in the lattice structure of the solvent is called ________________________.
Answer: Substitutional solid solutions
16.Fe3C in steel or cast iron is a ________________________.
Answer: Intermetallic compound
17.The weakest areas in a metal are _________________________ .
Answer: Grain boundaries
18._________________________ crystal structures exhibit similar packing density.
Answer: FCC and HCP
19.Lattice constant ‘a’ of the metals vary in the order of ___________________________ .
Answer: 2 ‐ 5 A0
20.Miller indices of basal planes in hcp crystal structure is _________________________ .
Answer: (0001)