Mechanical Behaviour Questions and Answers – Solid Solution Strengthening

This set of Mechanical Behaviour Multiple Choice Questions & Answers (MCQs) focuses on “Solid Solution Strengthening”.

1. Asymmetrical stress field results in _________ strengthening in comparison to non-symmetrical stress field.
a) Less
b) Higher
c) Very high
d) Equal

Explanation: A solute atom possesses non-symmetrical stress field when the lattice distortion is not equal in all directions. This stress field is developed due to defects. This type of stress field gives a higher degree of strengthening.

2. Match the following.

 (i) Substitutional solid solution (i) Long range interaction (ii) Interstitial solid solution (j) Short range interaction (iii) Elastic interaction (k) Non-symmetrical stress field (iv) Electrical interaction (l) Symmetrical stress field

a) i-k, ii-l, iii-i, iv- j
b) i-k, ii-l, iii-j, iv- i
c) i-l, ii-k, iii-i, iv- j
d) i-l, ii-k, iii-j, iv- i

Explanation: Substitutional solid solution possesses symmetrical stress field. While interstitial solid solution produces non-symmetrical stress field. Elastic interaction is of long range and electrical interaction is short range interaction.

3. Substitutional solute atoms result in __________ and interstitial atoms in __________
a) Symmetrical stress field, the symmetrical stress field
b) Symmetrical stress field, the non-symmetrical stress field
c) Non-symmetrical stress field, the symmetrical stress field
d) Non-symmetrical stress field, the non-symmetrical stress field

Explanation: Substitutional solid solutions possess symmetrical stress field. While interstitial solid solutions produce non-symmetrical lattice distortion. Hence it possesses non-symmetrical stress field.

4. Solid solution strengthening depends on the valency of solute atoms.
a) True
b) False

Explanation: For ionic materials, solid solution strengthening depends on various factors related to solute atoms. One of them is valency of solute atoms.
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5. For noticeable materials’ strengthening, alloying should be done with atoms of a solute material having ________
a) High shear modulus
b) High ductility
c) Low toughness
d) Low elastic modulus

Explanation: For higher degree of solution strengthening, alloying should be done with element having high shear modulus. It will increase the local shear modulus in the material. It increases the stiffness of the alloy.

6. According to Hume-Rothery rules, for unlimited solubility difference in atomic sizes of solute and solvent should be less than __________
a) 10%
b) 15%
c) 20%
d) 25%

Explanation: Hume-Rothery rules give some conditions for the unlimited solubility of the solute. One of the condition provides limitations to the size difference between solute and solvent atoms. It is given 15%.

7. Which of the following is an example of completely miscible binary systems?
a) Cu-Zn
b) Cu-Sn
c) Ag-Au
d) Fe-C

Explanation: Cu-Zn, Cu-Sn and Fe-C are binary systems having solubility limits. Ag-Au is a complete miscible binary system. It is because Ag and Au follow all conditions of Hume-Rothery rules.

8. Which of the following is not an example of isomorphous system?
a) Mo-W
b) Ag-Au
c) Fe-C
d) Cu-Ni

Explanation: Here, Fe-C is a limited solubility binary system. While Mo-W(bcc), Ag-Au(fcc) and Cu-Ni(fcc) are isomorphous systems. It means that these show extended solid solubility.

9. Steel is a _______ alloy.
a) Fe-C
b) Fe-Cr
c) Fe-N
d) Fe-Si

Explanation: Steel is an alloy of iron and carbon. Steels are of different types based on the presence of the amount of carbon and alloying elements. It includes low carbon steels, medium carbon steels and high carbon steels. Stainless steels and tools steels are examples of alloy steels.

10. A strength of material is proportional to __________
a) C
b) C1/2
c) C2
d) C-1

Explanation: Strength of material is proportional to C1/2. Here, C is the concentration of solute atoms. It is due to a large concentration of solute atoms, gives frequent obstacles to dislocations.

11. With an increase in the amount of zinc, electrical conductivity of copper ___________
a) Decreases
b) Increases
c) Remains constant
d) May increase or decrease

Explanation: With an increase in the amount of Zn in copper, it’s electrical properties deteriorate. Electrical conductivity decreases with an increase in zinc amount. It is due to the interaction of moving free electrons with strain field (generated by Zn atoms).

12. Solid solution strengthening improves ductility in general.
a) True
b) False

Explanation: Solid solution strengthening decreases ductility of metal in general. It is due to the introduction of strain fields by solute atoms in solvent matrix. This strain field causes checking of dislocations.

Sanfoundry Global Education & Learning Series – Mechanical Behaviour & Testing of Materials.

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