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# Materials Science MCQ’s – Slip Systems

1 - Question

Slip plane along with the direction of slip is called a slip system.

a) True

b) False

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Answer: aExplanation: Slip system is a combination of a slip plane and the slip direction for which the dislocation moves easily and leads to plastic deformation. For each crystal structure there exists its own set of slip systems.

2 - Question

How many slip system are there in FCC lattice?

a) 12

b) 6

c) 10

d) 18

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Answer: aExplanation: The number of slip planes are four and the number of slip direction are three in an FCC lattice. Therefore the total number of slip system is given by their multiplication that is twelve.

3 - Question

Slip planes do not occur where ______

a) Atom density is high

b) Atom density is low

c) Atoms are closely placed

d) direction of slip plane is the same as the translation vector which is the shortest

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Answer: bExplanation: Slip planes occur in planes where the atom density is high and hence the atoms are closely packed. Further, the direction of slip plane is the same as that of the translation vector which is the shortest.

4 - Question

Which law is related to slip plane and slip direction?

a) Bragg’s law

b) Fick’s law

c) Schmid’s law

d) Such a law doesn’t exist

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Answer: cExplanation: Schmid’s law gives us a relation between critically resolved shear stress and stress applied on the material. Where critical resolved shear stress is that component of shear stress which is in the slip direction.

5 - Question

Which of the following factors are more accurate when used for polycrystal metals?

a) Schmid’s factor

b) Taylor factor

c) Independent factor

d) Max factor

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Answer: bExplanation: Schmid’s factor is accurate for FCC crystal but for polycrystal metals use of the Taylor factor gives us a more accurate result.

6 - Question

Value of critical resolved shear stress for a given material at a given temperature ______

a) Increases with time

b) Decreases with time

c) Decreases harshly with time

d) Remains constant

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Answer: dExplanation: The critical resolved shear stress is independent of time and for a given material at a given temperature its value remains constant. It varies with a change in temperature.

7 - Question

Which of the following stresses is required for the slip to occur?

a) Tensile stress

b) Compressive stress

c) Critical resolved shear stress

d) Slip doesn’t occur due to stress

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Answer: cExplanation: A critical resolved shear stress is that component of shear stress which is in the slip direction and hence needed for a slip to occur. Tensile or compressive stress aren’t needed for a slip.

8 - Question

How many slip systems are there in BCC lattice?

a) 36

b) 48

c) 24

d) 18

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Answer: bExplanation: The number of slip plane is 48 for a BCC material. There are 6 planes of type {110} with 2 direction which gives us 12, in addition, there are 24 systems of {123} and 12 systems of {112}. Hence we get a total of 48.

9 - Question

How many slip systems are there in hexagonal closed packed crystal?

a) 3

b) 6

c) 9

d) 18

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Answer: aExplanation: In a hexagonal closed packed structure the slip is limited in comparison to bcc or fcc and allows slip in dense basal planes where the number of slip planes are calculated to be 3.

10 - Question

Slip is important for deformation to occur.

a) True

b) False

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Answer: aExplanation: The above statement is true. Slip is the mechanism that is followed by the dislocation when under plastic force to undergo deformation which can be seen on a three-dimensional level due to these microscopic slips.