Heterogeneous Nucleation MCQ

Test your knowledge with important Heterogeneous Nucleation MCQ and their applications. These MCQs are beneficial for competitive exams too. Explore 30 + more Heterogeneous Nucleation MCQs at Bissoy

• Nucleation on dislocations may also be assisted by solute segregation which can raise the composition of the matrix to nearer that of the precipitate.
  ক

  True

  খ

  False
• Which among the following curve represent the grain boundary?
  ক

  1

  খ

  2

  গ

  3

  ঘ

  Cannot be predicted
• In FCC crystals the a/2* unit dislocations can dissociate to produce a ribbon of stacking fault. Which among the following is as an example of the same? ->a/6* + a/6 b) a/2*->a/6* + a/6 c) a/2*->a/6* + a/6 d) a/2*->a/6* + a/6
  ক

  unit dislocations can dissociate to produce a ribbon of stacking fault. Which among the following is as an example of the same? ] a/2*->a/6* + a/6

  খ

  110

  গ

  110

  ঘ

  110
• A coherent nucleus with a negative misfit can reduce the critical volume free energy by forming a region of _________
  ক

  Compressive strain

  খ

  Compressive stress

  গ

  Tensile strain

  ঘ

  Tensile stress
• At very small driving forces, when activation energy barriers for nucleation are high, the highest nucleation rates will be produced by grain corner nucleation.
  ক

  False

  খ

  True
• The relative magnitudes of the heterogeneous and homogeneous volume nucleation rate is given as 0.5. Calculate the factor C/C1 (the number of atoms on heterogeneous sites relative to the number within the matrix)? (Consider exp (ΔG*(hom) – ΔG*(het)/kT) to be 1)
  ক

  0.5

  খ

  1.2

  গ

  0.25

  ঘ

  1.25
• What is special about the dark-field electron microscope micrograph?
  ক

  Precipitates can be imaged bright and matrix dark

  খ

  360 degree rotation is possible

  গ

  High speed imaging is possible

  ঘ

  Anti roller scheme available
• Excess vacancies are retained during the quench if the age hardening alloys are retained from______
  ক

  Dark texture

  খ

  Room temperature

  গ

  Low temperature

  ঘ

  High temperature
• If the ΔG* heterogeneous is given as 5kJ/mol and ΔG* homogeneous is given as 10kJ/mol. Calculate the shape factor?
  ক

  0.5

  খ

  1

  গ

  2

  ঘ

  2.5
• Calculate the shape factor if the angle tends to 90 degree?
  ক

  0

  খ

  1

  গ

  2

  ঘ

  4
• The ability of the grain boundary to reduce the value of critical free energy ΔG* depends on
  ক

  CosΦ

  খ

  SinΦ

  গ

  TanΦ

  ঘ

  CotΦ
• If we ignore the effect of misfit strain energy, which among the following could minimize the interfacial free energy?
  ক

  Optimum embryo texture

  খ

  Optimum embryo shape

  গ

  Optimum embryo volume

  ঘ

  Optimum embryo length
• Which among the following equation satisfies heterogeneous nucleation?
  ক

  ΔGhet = – V*(ΔGv – ΔGs) + Aγ – ΔGd

  খ

  ΔGhet = – V*(ΔGv – ΔGs) – ΔGd

  গ

  ΔGhet = – V*(ΔGv – ΔGs) + Aγ + ΔGd

  ঘ

  ΔGhet = – V*(ΔGv – ΔGs) + Aγ
• If the creation of a nucleus results in the destruction of a defect this will result in the_______
  ক

  Destruction of new nuclei

  খ

  Mass production of new nuclei

  গ

  Change of phase

  ঘ

  Reduction of activation energy barrier
• Nucleation in solids, as in liquids, in most cases is always __________
  ক

  Homogeneous

  খ

  Heterogeneous

  গ

  Mixed

  ঘ

  Semi heterogeneous