This set of Mechanical Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Solid Solution Strengthening”.
1. The metal with strong chemical affinity tends to form a good solid solution.
Explanation: When the chemical affinity between two metal is high, they tend to form a chemical bond with each other. Hence they form an intermetallic compound, not the solid solution compound.
2. The solubility limit of copper in zinc is much higher than the solubility of zinc in copper.
Explanation: The reverse of the statement is true. The solubility of zinc in copper is around 40 %, while the solubility of copper in zinc is less than 1%. This is because metal with lower valency dissolves in metal of higher valency.
3. Which of the following is not part of Hume Rothery rule?
a) The atomic radius of solute and solvent should not exceed more than 15%
b) The solute and solvent should have the same crystal structure
c) Both the metal have the same valency
d) There should be a significant difference in electronegativity of metals
Explanation: The solute and solvent should have similar electronegativity. Otherwise, they tend to form the intermetallic compound. The remaining rule is that they should have the same crystal structure.
4. Which of the following is not a long-range interaction about the solid solution strengthening?
a) Elastic interaction
b) Long-range order interaction
c) Stacking fault interaction
d) Modulus interaction
Explanation: The elastic interaction, long-range order interaction, modulus interaction are long-range interaction and relatively insensitive to the temperature effect. But the stacking fault interaction is short range.
5. Two-phase alloys consist of a hard and soft phase. If the hard phase is Continous along the grain boundary the resultant alloy will be _______
c) can be ductile or can be brittle
d) depends on the difference of hardness
Explanation: If the hard phase is along the grain boundaries, during deformation, the grain boundary will break upon applying stress and material will fail in a brittle manner. And vice versa is true for the soft phase.
6. Precipitation hardened metal alloys X consists of 95% phase-A and 5% phase-B. If the phase-B is in coarse precipitate form, the strength of the material will be higher as compared to when the phase-B is in fine precipitate form.
Explanation: If the precipitate is in coarse form the spacing between the precipitate particles will be higher and obstacle for dislocation movement per unit area will be low. So the fine precipitate dispersed throughout the matrix are best to improve the strength.
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