Physics of Metals in Metallurgy MCQ Questions and Answers

41

Fermi level of an atom refers to the

A) highest energy level occupied by the electron at absolute zero R B) energy level with a 50% probability of occupation C) energy of the outer most electrons D) none of the above

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Answer & Solution

Answer: Option A

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42

A dislocation line in a fcc crystal dissociates into two partials which have their Burger vectors as $$\frac{a}{6}\left[ {2\overline 1 \overline 1 } \right]$$ and $$\frac{a}{6}\left[ {11\overline 2 } \right],$$ Indicate the correct statement.

A) Burgers vector of the undissociated dislocation line is $$\frac{a}{2}\left[ {10\overline 1 } \right]$$ B) Burgers vector of the undissociated dislocation line is $$\frac{a}{2}\left[ {1\overline 1 0} \right]$$ C) Energy of each partial is proportional to $$\frac{{{a^2}}}{3}$$ D) Energy of the undissociated dislocation line is lesser than the sum of energy of two partials

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Answer & Solution

Answer: Option A

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43

In a single crystal of copper (lattice parameter 3.615°A). The distance between (11) planes (in °A) is

A) 1.807 B) 2.087 C) 2.556 D) 3.615

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Answer & Solution

Answer: Option A

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44

Match the following metals and alloys with their slip planes for room temperature deformations.

P. Austenitic stainless steel	1. None
Q. Molybednum	2. (110)
R. Cadmium	3. (111)
S. Tin	4. (0001)

A) P-2, Q-1, R-4, S-3 B) P-1, Q-2, R-4, S-3 C) P-4, Q-3, R-2, S-1 D) P-2, Q-1, R-3, S-4

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Answer & Solution

Answer: Option B

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45

The respective units for dislocation density and stress intensity factor are

A) m² and MPa.m B) m² and MPa.m$$^{\frac{1}{2}}$$ C) m^-2 and MPa.m$$^{\frac{1}{2}}$$ D) m^-2 and MPa.m

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Answer & Solution

Answer: Option C

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46

In a cubic lattice, the direction [123] is contained in the

A) plane (222) B) plane (123) C) neither A nor B D) both A and B

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Answer & Solution

Answer: Option D

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47

Shear modulus of copper is 45 GPa. Lattice parameter of copper is 3.61°A. The magnitude of burgers vector in copper is . . . . . . . . °A.

A) 2.54 B) 2.39 C) 2.20 D) 2.18

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Answer & Solution

Answer: Option A

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48

The direction [011] in cubic crystals

A) is perpendicular to the (111) plane B) lies within the (111) plane C) makes an angle of 30° with the normal to (111) plan D) Inakes an angle of 45° with the normal to (111) plane

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Answer & Solution

Answer: Option C

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49

For an FCC metal, the ratio of interplanar spacing obtained from the first two peaks of the X-ray diffraction pattern is

A) 1.91 B) 1.63 C) 1.41 D) 1.15

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Answer & Solution

Answer: Option D

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50

Which of the following statements are true about edge dislocations?
P. Edge dislocations do not have an extra half plane associated with them.
Q. The Burger vectors is perpendicular to the direction.
R. Edge dislocations can avoid obstacles by cross-slip.
S. Depending on geometry, parallel edge dislocations of opposite signs can attract or repel one another.

A) R B) P, Q, S C) Q, S D) Q, R

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Answer & Solution

Answer: Option C

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Physics of Metals in Metallurgy MCQ Questions and Answers | Metallurgical Engineering