This set of Materials Science Multiple Choice Questions & Answers (MCQs) focuses on “Interfacial Defects”.
1. Annealing twins which are found in metal have which type of crystal structure?
d) HCP and BCC
Explanation: Mechanical twins are observed in HCP and BCC crystal structure. A higher stored energy level favors the formation of annealing twins, but mainly at the beginning of the recrystallization regime.
2. At room temperature what is an approximate order of vibration frequency in vibration per second?
Explanation: Since amplitude vibration is few thousands of nanometre at room temperature. The frequency of the periodic motion is known as a vibration frequency.
3. In polymeric material the surface of which type of layer is considered to be an interfacial defect?
a) Chain ends
b) Short side branches
c) Main chain unit
d) Chain folded layer
Explanation: Chain folded layers create/ are boundaries between two crystalline regions which results in the interfacial defect.
4. Which type of boundary exists in multiphase materials across which there is a sudden change in physical/chemical properties?
a) Phase boundary
b) Chain folded layer
c) Domain wall
d) Grain boundary
Explanation: Chain folded layers are boundaries in case of polymeric materials. Domain wall deals with ferromagnetic and ferromagnetic materials and multiphase deals with phase boundary.
5. What is the density of polycrystalline specimen virtually identical to?
a) Singe crystal of different material
b) Single crystal of same material
c) Different crystal of different material
d) Different crystal of same material
Explanation: Single crystal of same material will have the same crystalline structure so their density will be identical.
6. Which type of boundary causes a constant angle of tilt between lattice planes of the same type in adjacent regions of the sample?
a) Twinning boundary
b) Tilt boundary
c) Grain boundary
d) Domain wall
Explanation: When a small grain boundary is formed due to tilt in the angle of orientation is called tilt boundary. A Twin Boundary happens when the crystals on either side of a plane are mirror images of each other.
7. Volume defect or bulk defects are which dimension defect?
a) 1 dimension
b) 2 dimension
c) 3 dimension
d) 4 dimension
Explanation: Volume defects are three dimensional defects. Interfacial defects are two dimensional. In short volume defect is an application of interfacial defect.
8. Interfacial defect does not include which of the following defect?
a) Grain boundary
b) Twin boundary
c) Phase boundary
d) Volume defect
Explanation: Interfacial defects are 2 dimensional defects whereas volume defect is 3 dimensional defects. Grain boundary, Twin boundary and Phase boundary are types of interfacial defect.
9. What will be the interfacial energy for domain wall?
a) Greatest compared to other interfacial defects
b) Least compared to other interfacial defects
c) Less than external surface but more than other interfacial defects
d) Less than the external surface and grain boundary but more than other interfacial defects
Explanation: Domain wall is the boundary that separates the region having a different direction of magnetization in case of ferromagnetic and ferrimagnetic material. Hence interfacial energy is least in case of a domain. As magnetization energy is less compared to other energies.
10. Which dimension defect are interfacial defects?
a) 2 dimension
b) 1 dimension
c) 3 dimension
d) 4 dimension
Explanation: Interfacial defect are boundary defect that has 2 dimension and normally separate regions of the materials that have different crystal structures and/or crystallographic orientations. These imperfections include external surfaces, grain boundaries, twin boundaries, stacking faults, and phase boundaries.
Sanfoundry Global Education & Learning Series – Materials Science.
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