MCQOPTIONS
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MCQOPTIONS
This section includes 13 Mcqs, each offering curated multiple-choice questions to sharpen your Phase Transformation knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
If unit area of grain boundary advances a distance 4mm, the number of moles of material that enter in the grain B is 4* (1/ 8(mm3/mol)) and the free energy released is given by_______ ( G =10kJ/mol) |
| A. | 5 kJ/mol*mm<sup>2</sup> |
| B. | 20 kJ/mol*mm<sup>2</sup> |
| C. | 10 kJ/mol*mm<sup>2</sup> |
| D. | 40 kJ/mol*mm<sup>2</sup> |
| Answer» B. 20 kJ/mol*mm<sup>2</sup> | |
| 2. |
On heating to a sufficiently high temperature, what happens to the new grains? |
| A. | They fall off |
| B. | They disperse |
| C. | Velocity decreases |
| D. | They grow and nucleate |
| Answer» E. | |
| 3. |
It is possible that the higher mobility of special grain boundaries plays a role in the development of recrystallization textures. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 4. |
For low mole fractions of solute in the matrix 0.5 (Xo), the boundary solute concentration Xb (in 10-12) is given by_____ ( G =105kJ/Mol, T =505K) |
| A. | 6.94 |
| B. | 7.94 |
| C. | 6.14 |
| D. | 9.80 |
| Answer» B. 7.94 | |
| 5. |
During recrystallization, the boundaries between the new strain-free grains and the original deformed grains are acted on by a force G /V where, in this case, G is due to the difference in dislocation strain energy between the two grains. |
| A. | False |
| B. | True |
| Answer» C. | |
| 6. |
Calculate the chemical potential if the molar volume is given as 5 mm3/mol? (Given the value of radius as 4mm and the interfacial energy is 8 kJ/mm2? |
| A. | 10 |
| B. | 20 |
| C. | 24 |
| D. | 22 |
| Answer» C. 24 | |
| 7. |
Calculate the pulling force F, if the chemical potential and the molar volume is given as respectively? |
| A. | G-V |
| B. | G+V |
| C. | G/V |
| D. | G*V |
| Answer» D. G*V | |
| 8. |
Under which of the following circumstances the grain boundary behaves as a thin soap film? |
| A. | When the boundary energy is dependent on the orientation |
| B. | When boundary energy is 0 |
| C. | When the torque is greater than zero |
| D. | When the boundary energy is independent on the orientation |
| Answer» E. | |
| 9. |
What will be the torque acting on the boundary if the boundary happens to be at the orientation of a cusp in the free energy? |
| A. | 500 Nm |
| B. | Greater than 500 Nm |
| C. | Less than 500 Nm |
| D. | Zero |
| Answer» E. | |
| 10. |
What is the need for a grain boundary in an annealed material? |
| A. | To control the grain size |
| B. | To maintain its shape |
| C. | It can produce a stable equilibrium at the grain edges |
| D. | During annealing it produce a metastable equilibrium at the grain boundary intersections |
| Answer» E. | |
| 11. |
When two grains meet in a plane it is known as _____ |
| A. | Grain corner |
| B. | Grain boundary |
| C. | Grain edge |
| D. | Grain center |
| Answer» C. Grain edge | |
| 12. |
When the two grains are related by a rotation about a <110> axis, there are several large-angle orientations which have significantly lower energies than the random boundaries. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 13. |
When the two grains are related by a rotation about a <100> axis, it can be seen that most high-angle boundaries have _____ |
| A. | Almost same energy |
| B. | Different energy |
| C. | Highly ordered structure |
| D. | Nothing can be said about their energies |
| Answer» B. Different energy | |